Joe Biden swept Tuesday’s primaries, winning the popular vote in Michigan, Missouri, Mississippi and Idaho. The former vice president’s campaign has gained momentum after overtaking Senator Bernie Sanders in the Super Tuesday primaries last week, and he is now in position to win the democratic nomination.

Sanders won in North Dakota and currently leads Biden by a narrow margin in Washington, where approximately only 70% of precincts have reported results. Washington’s 89 delegates could play a significant role in the Sanders campaign as he fights to stay in the race. Sanders stated Wednesday that he would not be dropping out of the race and that Tuesday night was “not a good night for our campaign from a delegate point of view” but that he is looking forward to Sunday’s debate with Biden, the first one-on-one debate of the election.

Biden’s victory in Michigan, a state where Sanders won in a surprising upset against Hillary Clinton in 2016, was key to distancing himself even further from Sanders. Michigan was the largest state up for grabs in the March 10 primary with 125 delegates. Only about 53% of the Democratic delegates remain, and after March 17 less than 39% will be unpledged.

Biden won by a landslide in other states including Mississippi and Missouri, where CNN estimates show Biden leading Sanders by at least 65% and 25% respectively. CNN exit polls also show Biden gaining support in Michigan among a number of groups previously supportive of Sanders, including white, college-aged males, those who prioritize healthcare (of whom nearly 6 in 10 voted for Biden), and almost three-quarters of those who oppose private insurance.