Does Bernie Sanders really have a shot at winning the Democratic nomination? The Vermont senator’s dark horse candidacy, once dismissed as a political sideshow, is now expanding beyond its traditional base of support in New England, threatening what was once considered a “coronation” for Hillary Clinton.

In the latest Quinnipiac poll, Sanders was in a statistical dead heat with former Secretary of State Clinton, with 42% of Democrats nationwide saying they’d back him, compared to 44% for Mrs. Clinton. Just two months ago the same poll had Clinton leading Sanders by a whopping 31 points, 61 to 30.  

The Sanders campaign has enjoy significant momentum following his blowout 22 point victory over Clinton in the New Hampshire primary earlier this month.  

But political observers largely assumed the Vermont senator’s campaign would lose steam as the Democratic primaries shifted from the overwhelmingly white electorates in Iowa and New Hampshire to South Carolina and Nevada, where black and Hispanic voters make up much of the Democratic electorate.

New polling, however, shows that Clinton’s once seemingly insurmountable lead among these two groups has dwindled.  Both nationwide and in South Carolina, Sanders’ support from non-white voters has surged by 50% since January.

That is a major factor in the tightening race nationwide and is making the Nevada primary and South Carolina caucus far more competitive than the Clinton campaign anticipated.

In South Carolina, where Clinton led by 50 points in December, the former First Lady now leads by only 18 points according to the latest CNN/ORC poll. In Nevada, Clinton’s 23 point lead has completely disappeared, with the race now in a dead heat.