Hillary Clinton has won the Democratic primary in Mississippi, while Senator Sanders clinched Michigan. Republican presidential hopeful Donald Trump meanwhile has won both states for the GOP.
Former Secretary of State Hillary Clinton continued in securing her position as the front-runner for the Democratic Party's pick for presidential candidate, scoring votes especially among the African-American population of the southern state of Mississippi, who favor the Clinton dynasty over Sanders.
Hillary Clinton appears to be gaining a lead on Bernie Sanders, but the primaries continue to bring up surprises
But her battle with Bernie Sanders appears to be far from over, as most news agencies and outlets reported the senator from Vermont to have made gains in the Midwestern state of Michigan following a close race - a state, which had originally been projected to give Clinton a lead over Sanders.
Donald Trump meanwhile managed to deepen his grip on the Republican nominating contest in both Mississippi and in Michigan.
Four states in total are voting in primaries, with Republicans also holding pre-election events in Idaho and Hawaii in addition to the polls in Michigan and Mississippi.
According to US media, Trump's conservative rival Ted Cruz won Idaho, taking almost 42 percent of the vote ahead of Trump's 28.9 percent and 18.1 percent for Senator Marco Rubio.
Trump preparing for the showdown
Trump's gains in Michigan and Mississippi could make March 15 the decisive day's voting, when the delegate-rich states of Ohio, Florida, Illinois, Missouri and North Carolina host their Republican primaries. However, Trump still has a long way to go to reach the required number of delegates. It might still take weeks for either party's presidential nominations to be clear.
Republican front-runner Donald Trump is hoping to restore his campaign there after suffering a number of public image setbacks in the past week, which have also resulted in a barrage of attacks from other Republican Party members. Senator Ted Cruz has been positioning himself as the prime alternative to Trump, whose belligerent style has been making headlines.
Meanwhile, Senator Marco Rubio of Florida appears to lag in Michigan polls and could fall out of the race if he fails to win in his home state of Florida later in March.
ss/rc, msh (Reuters, AP, AFP, dpa)