Former vice president Joe Biden, who led Sanders in a Post-ABC national poll in January, has seen a sharp drop in his support after finishing fourth in the Iowa caucuses and fifth in the New Hampshire primary. Biden is now in a battle for second place with former New York mayor Mike Bloomberg and Sen. Elizabeth Warren (D-Mass.), The Washington Post reported.

Former South Bend, Ind., Mayor Pete Buttigieg, who won the state-delegate-count battle in the Iowa caucuses and came a close second to Sanders in New Hampshire, is in single digits nationally, roughly even with Sen. Amy Klobuchar (D-Minn.), whose surprise third-place finish in New Hampshire further scrambled the Democratic contest.

The poll underscores how quickly support for candidates can change in national polls on the strength of results from individual primaries and caucuses. The findings come on the day of a Democratic debate in Las Vegas that will include Bloomberg on the stage for the first time and represents a high-stakes gamble for all the candidates.

The poll also comes just days ahead of the third contest on the calendar, Saturday’s Nevada caucuses, with the South Carolina primary to follow on Feb. 29. After South Carolina, the campaign goes national, with 14 states holding contests on March 3, Super Tuesday, and crucial primaries in a variety of big states later in the month.

The Post-ABC poll shows Sanders, who got more votes in Iowa than any other candidate ahead of his narrow win in New Hampshire, with the support of 32 percent of Democrats and Democratic-leaning registered voters. That is an increase of nine percentage points since January. He holds double-digit leads among both women and men, as well as among those who say they are certain to vote in their state’s primary or caucuses.

Biden, who was at 32 percent support in January, has fallen to 16 percent in the new survey. He faces significant hurdles as he attempts to mount a comeback, with his hopes pinned on success in Nevada and especially South Carolina, where he had long been the favorite of African American voters who make up a hefty majority of the Democratic electorate there.

Bloomberg, who is skipping the first four states but has poured hundreds of millions of dollars into television ads in states with primaries in March, stands at 14 percent, up from 8 percent in January. He has only recently begun to receive significant criticism from the other candidates, however.

Warren saw no change in her national support, remaining at 12 percent. Buttigieg, despite his strong performances in Iowa and New Hampshire, runs fifth nationally at 8 percent, ticking up from 5 percent a month ago. Klobuchar stands at 7 percent in the new national poll, up from just 3 percent. Buttigieg and Klobuchar face a similar challenge, which is to appeal to a broader coalition of voters in the coming two early-state contests.

Biden’s poor finishes in Iowa and New Hampshire appear to have robbed him of his image as the most electable against President Trump in November — the chief attribute he has used to define his campaign.

By a wide margin, 58 percent to 38 percent, Democrats say they would rather nominate a candidate who can defeat Trump than one who agrees with them on major issues.

Electability is a subjective judgment, however, and the former vice president is paying the price for his failure to draw more significant backing from voters in the first two states. A month ago, 38 percent of Democratic-leaning adults cited Biden when asked which candidate has the best chance to defeat Trump, making him their top choice in that regard. Today that has dropped by half, to 19 percent.

In the new poll, Sanders is seen as the most electable, cited by 30 percent of Democratic leaners as best situated to beat Trump. Bloomberg is cited by 18 percent on this question, with no other Democrat close to double digits.

In the past month, Biden has lost support among three key constituency groups: African Americans, older voters, and whites without college degrees, previously the bulwarks of his campaign. In a Post-Ipsos poll this year, Biden was backed by 48 percent of African American voters. Today that has fallen to 31 percent. Compared with January’s Post-ABC poll, his support has been cut nearly in half among voters over age 50 and stands at 20 percent; among non-college whites, support for Biden plummeted from 33 percent to 11 percent.

Sanders has seen a big jump in support among voters under age 50 and is now backed by 50 percent of that group, up from 34 percent in January. He holds a 3-to-1 lead over his rivals among these voters. Sanders also has more than doubled his support among black voters and has gained among whites without college degrees.

Bloomberg’s growth was fueled by more support among older voters and among white voters with college degrees. Buttigieg, Warren, and Klobuchar saw no significant shifts in their coalitions.