The center left Social Democratic Party, the third group in Germany's governing coalition, have yet to decide whether they will accept the CDU/CSU deal on migrant policy. DW has the news as it happens.
The main points:
All times in Central European Summer Time (UTC+2)
00:29 Nothing more expected from the SPD tonight. Leaving the coalition committee meeting early Tuesday, the head of the group, Andrea Nahles, said many issues still needed to be clarified before the SPD could approve the CDU/CSU deal.
"We find [the compromise] good because we are now back on a practical level. That's something we sorely missed in recent weeks," said Nahles. "We'll take the time we need to come to a decision." She is expected to continue the discussions at the chancellery on Tuesday evening.
22:52 And that meeting between the CDU, the CSU and SPD has already begun.
22:38 It is still unclear if the SPD will accept such a deal. They are meeting later tonight.
22:36 Merkel expressed her satisfaction with the agreement, saying they had found "a really good compromise after a hard struggle."
"This (deal) preserves the spirit of partnership in the European Union and at the same time is a decisive step towards organizing and controlling secondary migration."
22:34 The content of the deal is as follows:
1) At the German-Austrian border there should be a new border regime, it should ensure "that we prevent asylum seekers whose asylum procedures are the responsibility of other EU countries from entering the country".
2) Transit centres will be set up. From there, asylum seekers should be sent directly to the responsible countries. However, this should not be done without a consensus, but on the basis of administrative agreements, for example.
3) In cases where such agreements can not be reached, they would nevertheless be rejected - "on the basis of an agreement with the Republic of Austria."
22:24 The two parties will reportedly set up transit centres at the German-Austrian border for asylum seekers who are already registered in another EU country. Asylum seekers will then be sent back to responsible countries.
22:21 Seehofer: "I am glad that this agreement has been reached. It has once again become clear that it is worth fighting for a conviction. And what follows now is a very sustainable and clear agreement for the future. The agreement meets my expectations on all three points."
22:18 Seehofer says he will remain in his position. They have a clear solution to stopping illegal immigration at the German-Austrian border.
22:14 Seehofer has announced they have made a deal. "We have made a deal"
22:10 Bild is reporting the CDU and CSU apparently want to announce their results in a joint statement.
22:04 DPA are reporting Merkel and Seehofer have agreed on a compromise in the migration dispute.
21:53 Citing unnamed politicians present at the CSU-CDU talks, Germany's DPA news agency said that nobody was talking about Seehofer's offered resignation at the meet.
Some delegates believe that Seehofer's silence indicates him staying on as interior minister, the agency said.
21:46 The representatives of the CSU and the CDU are considering so-called "transit centers" as a way to compromise on migrant policy, according to German newspapers Augsburger Allgemeine and Bild.
The centers, possibly near the border, would give the German authorities a chance to work on expelling asylum seekers who already applied for asylum elsewhere in the EU.
21:27 As talks between leaders of the CSU and the CDU continue, the two groups temporarily separated to discuss "compromise ideas," according to the Reuters news agency.
21:19 Germany's Development Minister Gerd Müller says Merkel and Seehofer are in dispute over a "minor point" of turning asylum seekers away at the border.
"We cannot put the coalition in jeopardy over this point," he added. "This just cannot happen, to have Germany, Europe go into a crisis over that."
Preserving the CSU/CDU coalition is "the highest priority," according to the minister.
20:40 The agreement between the two conservative parties, the CDU and the CSU, could come today or tomorrow, but also "sometime this week," senior CDU member Mike Mohring told the German public broadcaster ARD. In turn, Andrea Nahles – leader of the Social Democrats, the coalition's junior partner in government – said the decision needed to happen today.
19:51 German newspaper Westfälische Nachrichten comments on Seehofer's threat to resign, saying that the 68-year-old politician has placed himself "very close to making him a permanent object of ridicule."
"Will he take Merkel down with him out of mixture of bitterness and revenge?" the paper wonders.
19:37 The head of Germany's SPD, Andrea Nahles, dismissed Seehofer's "master plan" on immigration, saying that her party would only be guided by the coalition agreement with the two conservative parties.
18:06 Horst Seehofer and other top CSU representatives have started the last-ditch meeting with Angela Merkel and other CDU leaders in Berlin.
"I hope it will still be light out when I go back outside," Seehofer told reporters gathered outside the CDU's headquarters.
DW's Fabian von der Mark captured the moment at the entrance to the CDU's Konrad-Adenauer-Haus.
17:30 The CDU-CSU meeting, originally scheduled for 5 pm, has been delayed while senior CSU members continue their consultations behind closed doors.
17:24 Speaking to the Süddeutsche Zeitung, Seehofer said he cannot imagine being "thrown out" by the person he had "helped get in the saddle."
"I will not be fired by the chancellor who is only chancellor because of me," he told the paper on Monday afternoon.
17:18 Germany's SPD has asked for an emergency session of the parliament on Tuesday morning.
17:13 Vice chairman of the pro-business FDP party, Wolfgang Kubicki, has called for a new election. "Both the Union and the SPD are right now doing everything to demonstrate that they do not fit together anymore," he told Berlin's Inforadio.
17:08 EU Budget Commissioner Günther Oettinger, a member of the CDU, says the CSU has the option of naming another minister if Seehofer resigns. This would allow it to continue its partnership with the CDU, Oettinger told Germany's SWR regional broadcaster.
16:09 According to a German media reports, Merkel and Seehofer have begun their meeting with the head of the German parliament, Wolfgang Schäuble, in his Berlin office.
15:49 Former CSU leader Erwin Huber believes Seehofer's resignation is now "unavoidable," but adds that the move should not jeopardize the coalition.
15:34 A meeting of lawmakers representing all three parties of the grand coalition – the CSU, the CDU, and the SPD – has been set for 10 p.m. on Monday.
15:28 Chancellor Angela Merkel expressed her hopes that the rift between the CSU and the CDU would be over by late Monday. "There is a strong desire to solve it," she said at the summit of conservative lawmakers, according to DW's Fabian von der Mark.
15:19 The head of CSU's parliamentary group, Alexander Dobrindt, says the dispute can be overcome. The decades-long political alliance between the CSU and the CDU has "created a strong bond that can have enough power to overcome and overrule a conflict over something solvable."
14:47 A coalition committee of CDU, CSU and SPD members of government is due to meet late on Monday, after a meeting of CDU and CSU leaders in the afternoon.
14:37 The parliamentary groups of the CDU and the CSU meet in Berlin with Chancellor Angela Merkel, but without Interior Minister Horst Seehofer.
14:24 The Bavarian Industry Association (vbw) has called on the government to reach a compromise on migration. "There's a lot at stake for our country," its president, Alfred Gaffal, said on Monday.
He said the debate about migration was too dominant and that the political focus needed to shift to the challenges of digitalization, skills shortages, trade conflicts and demographic change.
13:53 What do refugees in Germany think about German migration policy? Read more here: How do refugees view Seehofer's tougher migration plan?
13:47 Left party co-leader Bernd Riexinger accuses the CSU of "doing the business of the [far-right] AfD." He says the CSU's policies on migration had caused a "shift to the right" in Germany and only made the CSU "capable of being annexed" by the AfD.
13:45 The Free Democrats (FDP) are calling for a "migration summit" involving representatives from the federal, state and municipal levels. FDP head Christian Lindner said such a summit was necessary as the current government was unable to solve the problem.
13:37 #MERSEE emerges as football-like hashtag on Twitter for "a match of different sorts," DW's Kate Brady tweets.
13:22 Confusion over Seehofer's so-called "master plan for migration": An Interior Ministry spokeswoman says when Interior Minister Seehofer presented it to his CSU party on Sunday, he did so as head of the CSU, not as interior minister.
The Interior Ministry, she added, was working on its "master plan" and that it was a work in progress.
13:11 Left party MP Anke Domscheidt-Berg harshly criticizes Seehofer in an interview with DW: "Seehofer is acting in a way that endangers democracy, at a time when democracy and trust in its institutions must be strengthened."
12:45 SPD head Andrea Nahles stresses that her party wants a "humanitarian refugee policy, but with a healthy dose of realism."
12:39 SPD head Andrea Nahles says the CSU is on "a dangerous ego trip" and that the SPD executives cannot stop shaking their heads because of this crisis.
She adds that "my optimism was greater two days ago," when asked if she thought the CDU and the CSU could overcome their differences.
12:37 SPD lawmaker Rolf Mützenich tells DW: "Through serious negotiations, we laid solid foundations for good government policy. Large parts of the CDU and CSU are putting this at stake because of personal and political sensitivities."
12:33 What are the SPD's plans on migration? Read more here:SPD presents 5-point plan ahead of big decision
12:26 SPD head Andrea Nahles tell journalists that things can't go on like this when asked when the SPD may start calling the coalition into question, says DW's Sabine Kinkartz.
12:24 Coalition partner SPD calls for a coalition committee to tackle the current crisis
12:18 One of Germany's leading economic institute, the ZEW, points out that an EU-wide, coordinated, migration policy benefits the economy. "Germany going it alone at this point would therefore run counter to German interests."
12:14 Foreign Minister Heiko Maas (SPD) calls the row between the CSU and the CDU "damaging" for Germany and the government.
12:06 It's a baffling crisis for foreign journalists, too: DW's Sabine Kinkartz tweets from Monday's Federal Press Conference in Berlin. A Dutch journalist says "I don't really understand what's happening between the CDU and the CSU." It seems the government's spokespeople can't help there either...
11:34 So, what are the likely scenarios if Seehofer follows through with his offered resignation? Read more here: What happens to the German government if Horst Seehofer resigns?
11:18 Bundestag President Wolfgang Schäuble (CDU) reportedly said his party was "on the brink" during the ongoing CDU executives' meeting, according to the Reuters news agency, citing people familiar with the talks.
11:17 Social Democrat MP Sonja Steffen tells DW: "I hope that the CSU and especially Horst Seehofer come to their senses. The result of the EU summit was a bridge and a good basis for ending the row within the conservative camp. For that reason, the renewed bickering is all the more incomprehensible."
11:02 Center-right and far-right parties are also unimpressed by the CSU:
Alternative for Germany (AFD) Parliamentary Group Leader Alice Weidel: "Horst Seehofer and the CSU have performed a cheap bit of theater. The back and forth and the cancellation of his resignation as interior minister were all staged."
Free Democratic Party Chairman (FDP) Christian Lindner: "On the question of policy, I can understand rejecting what Ms. Merkel negotiated. But on the question of power, it's unprofessional and plunges our country into crisis and paralysis."
11:00 The interior minister for the state of Bavaria, Joachim Herrmann, says claims that Germany's border with Austria would be closed are incorrect, Reuters reports.
10:46 Left-wing politicians are calling for Seehofer to resign as interior minister.
Green party Parliamentary Leader Anton Hofreiter: "Anyone who treats his responsibility for the country so cavalierly and egotistically can no longer responsibly perform his ministerial duties."
Former Foreign Minister Sigmar Gabriel (Social Democrats): "Anyone who acts this way squanders every ounce of trust citizens have in our political system." He told Spiegel magazine "That's why he has to go now."
10:41 Bavarian Premier Söder stressed that "one thing is clear: For us, the stability of the government is not at risk."
10:33 The German press is, by and large, unimpressed with Horst Seehofer.
Spiegel: "If he remains interior minister, his credibility is gone. If he resigns, the same thing is true."
Welt: "Seehofer backtracks at 1 a.m. – and the chaos is complete."
Süddeutsche Zeitung: "Seehofer's days as the head of the CSU are numbered…Seehofer's final political goal: If I go down, so does Merkel."
But Bild newspaper is offering some words of support: "This battle has to be."
10:15 Bavarian Premier Markus Söder confirms in several interviews that he wants to keep the CDU/CSU alliance. "We do not want to leave the government nor end the cooperation with the CDU."
The CDU leadership has issued a statement saying "we are still hoping for an agreement."
10:00 Here's the latest analysis from our DW studios this morning. DW political correspondent Peter Craven debriefs on air.
Normally "cool, calm and collected, she's now being drawn into what is being described as an endgame with Horst Seehofer," Craven says. "That's not the Angela Merkel world as we know it."
09:57 We're going to have to be patient for the day's main meeting. Angela Merkel and her interior minister are expected to meet at 5 p.m. this evening. Seehofer has offered his resignation, but said in the early hours of the morning that he still hoped for a solution.
09:40 The CDU's leading figures are meeting in Berlin in a last-ditch attempt to break the deadlock with Bavarian sister party, the CSU, over the government's migration policy.