Senator Bernie Sanders has delivered an upset in Michigan, unexpectedly taking the state against Hillary Clinton.
The win comes after Sanders was victorious in Maine, as well as Kansas and Nebraska over the weekend.
"I am grateful to the people of Michigan for defying the pundits and pollsters and giving us their support," Sanders said of the result.
“What tonight means it that the Bernie Sanders campaign, the people’s revolution that we are talking about, is strong in every part of the country and frankly we believe that our strongest areas are yet to happen,” he added.
Still, Clinton overwhelmingly won in Mississippi, increasing her overall lead. Clinton is still favourite to become the next President.
On the Republican side of the race, Donald Trump won Michigan and Mississippi, extending his lead over other candidates.
Ted Cruz managed to win Idaho, however. Last weekend Trump and Cruz called for a one-on-one battle, with Cruz stating "as long as the field remains divided, it gives Donald an advantage".
Senator Marco Rubio, for his part, just can't catch a break. He came fourth in Michigan and Mississippi, just one week before a win in his home state of Florida.
That won't be easy for Rubio, given Trump is still leading in the polls there.
So analysts and commentators reckon that only Cruz will be able to stop Trump, who has been heavily criticised by the Republican establishment.