Sen. Bernie Sanders is leading the 2020 pack while former Mayor Michael Bloomberg has surged to third, a national poll by Quinnipiac showed Monday.

By the numbers: Quinnipiac found Sanders with 25%, former Vice President Joe Biden with 17%, Bloomberg with 15%, Sen. Elizabeth Warren with 14%, former Mayor Pete Buttigieg with 10% and Sen. Amy Klobuchar with 4%. No other candidate polled above 2%.

Why it matters: Sanders is set to come in a narrow second in Iowa behind Buttigieg, assuming pending recanvasses don't change results. But the senator is heading into New Hampshire Tuesday with strong polling, and he is a leading contender in next week's Nevada caucuses.

But Bloomberg remains a looming wild card for the Democrats. He's opted to ditch campaigning in the early states, instead fighting for wins on Super Tuesday and beyond.

Between the lines: Biden is collapsing among black voters, and Bloomberg gained most of the difference.

December Quinnipiac nationwide of black primary voters:

Biden: 51%

Sanders: 13%

Warren: 12%

Bloomberg: 4%

February Quinnipiac nationwide of black primary voters:

Biden: 27%

Bloomberg: 22%

Sanders: 19%

Warren: 8%

Buttigieg has struggled to poll with minority voters. While he did well in primarily white Iowa, his struggles among the group could become apparent in upcoming, more diverse states.

Go deeper: New Hampshire polls show Sanders, Buttigieg on top in final stretch