A little over one third of all surveyed voters said they didn’t know or had no opinion about which of the remaining Democratic candidates was most electable. But 16 percent picked Sanders as the most electable, followed by a cluster of three of his more moderate opponents.

Bloomberg came in second when it came to electability, with 13 percent, followed by former Vice President Joe Biden with 12 percent and former South Bend Mayor Pete Buttigieg with 10 percent.

The former New York mayor has sought to paint himself as the ideal moderate to defeat Trump, sinking his vast fortune into digital and TV ads. Those efforts have not yet paid off within the party, according to Wednesday’s poll, which found the gap between Sanders and his opponents doubled among Democratic primary voters, with Bloomberg dropping to third.

Bloomberg “may be ascending in the polls, but he's trailing when it comes to the electability argument," said Tyler Sinclair, Morning Consult's vice president. "Notably, 24 percent of Democratic primary voters selected Bernie Sanders as the most electable Democratic presidential candidate, compared with 18 percent who said Joe Biden and 16 percent who said Michael Bloomberg."

Bloomberg has spent the vast majority of his last-minute candidacy training his focus on the current occupant of the White House — drawing a barrage of attacks from Trump himself that could in turn bolster his electability argument.

But because of party-dictated debate qualifying criteria that barred him from appearing in previous primary debates, he's largely been able to evade the type of live cross-examination that the contests can offer. And that's an opportunity Bloomberg's competitors are sure to seize Wednesday.

Bloomberg hasn't appeared on a debate stage in over a decade and his own team has worried about how he'll perform and whether a shaky performance could blunt his momentum.

The POLITICO/Morning Consult poll was conducted from Feb. 15-17 among a national sample of 1,990 registered voters. Results from the full survey have a margin of error of plus or minus 2 percentage points.

Morning Consult is a nonpartisan media and technology company that provides data-driven research and insights on politics, policy and business strategy.

More details on the poll and its methodology can be found in these two documents: Toplines | Crosstabs

