WASHINGTON — Former Mayor Michael R. Bloomberg of New York has qualified for Wednesday’s debate in Las Vegas, the first time the billionaire will appear onstage alongside his Democratic presidential rivals.
A national poll from NPR, PBS NewsHour and Marist released on Tuesday showed Mr. Bloomberg with 19 percent support among Democrats and Democratic-leaning independents, good enough for second place behind Senator Bernie Sanders of Vermont, who had 31 percent, and earning him his best result in a debate-qualifying national poll yet.
Mr. Bloomberg will face off Wednesday night against Mr. Sanders; Senators Elizabeth Warren of Massachusetts and Amy Klobuchar of Minnesota; former Vice President Joseph R. Biden Jr.; and Pete Buttigieg, the former mayor of South Bend, Ind.
The debate, which will air at 9 p.m. Eastern time, will be hosted by NBC News, MSNBC, Telemundo and The Nevada Independent.
Mr. Bloomberg’s result marked a substantial surge since the NPR/PBS NewsHour/Marist poll in December, when he received only 4 percent support. Mr. Sanders’s support has also increased significantly since that poll, which showed him with 22 percent.
Mr. Biden came in third in the new poll, with 15 percent, followed by Ms. Warren at 12 percent, Ms. Klobuchar at 9 percent and Mr. Buttigieg at 8 percent. The poll surveyed 527 Democrats and Democratic-leaning independents by phone Feb. 13-16 and had a margin of sampling error of plus or minus five percentage points.
The latest national polling average calculated by The New York Times, which was released late last week, put Mr. Bloomberg at 10 percent, behind Mr. Sanders, Mr. Biden and Ms. Warren.
Mr. Bloomberg formally entered the race in November, nearly a year after most of the other candidates. He failed to make the cut for the past several debates in part because he is not accepting outside contributions for his campaign. But new rules announced by the Democratic National Committee opened the door to his participation, as they enabled candidates to qualify for the Las Vegas debate, as well as the one that will take place on Feb. 25 in Charleston, S.C., without meeting a donor threshold.
He is certain to face onstage criticism from his rivals Wednesday night, especially Mr. Sanders and Ms. Warren, the two candidates who are not appearing at private fund-raisers and who have made targeting billionaires central to their campaigns.
Last week in Virginia, Ms. Warren told supporters that Mr. Bloomberg should not be the Democratic Party’s nominee because of his past remarks linking the end of redlining, a discriminatory housing practice, to the financial crisis.
Both Ms. Warren and Mr. Sanders previewed their arguments against Mr. Bloomberg in remarks on Tuesday.
“Anybody here with $60 billion, you can run for president, and you can buy the airwaves,” Mr. Sanders said in a speech in Reno, Nev. “That is called oligarchy, not democracy.”
Ms. Warren was more pointed. “It’s a shame Mike Bloomberg can buy his way into the debate,” she wrote on Twitter. “But at least now primary voters curious about how each candidate will take on Donald Trump can get a live demonstration of how we each take on an egomaniac billionaire.”
Mr. Bloomberg’s campaign manager, Kevin Sheekey, confirmed on Tuesday that Mr. Bloomberg would take part in the next debate.
“Mike is looking forward to joining the other Democratic candidates onstage and making the case for why he’s the best candidate to defeat Donald Trump and unite the country,” Mr. Sheekey said. “The opportunity to discuss his workable and achievable plans for the challenges facing this country is an important part of the campaign process.”
Also on Tuesday, Monmouth University released a poll of Virginia voters showing Mr. Bloomberg and Mr. Sanders tied at 22 percent each and leading the field. With 99 delegates at stake, Virginia is the fourth-largest prize on the Super Tuesday calendar, and Monmouth’s is the first poll to have been taken there since the summer. It is one of the first polls of any state in which Mr. Bloomberg has broken 20 percent. (The Virginia poll has no effect on qualifications for this week’s debate.)
The other two candidates in the race, the billionaire Tom Steyer and Representative Tulsi Gabbard of Hawaii, appeared unlikely to receive the requisite 10 percent support in four national qualifying polls, or 12 percent in two polls taken in Nevada or South Carolina, before the debate deadline.
Candidates were also able to qualify for the Nevada and South Carolina debates by winning at least one delegate in the Iowa or New Hampshire contests; that is the path Ms. Klobuchar and Mr. Buttigieg, who have not met either polling threshold, followed to get their invitations to the stage in Las Vegas.
Mr. Bloomberg has spent over $300 million on TV advertising nationwide — more than the rest of the field combined — and he has seen his standing steadily rise in national polling as voters have been saturated by his campaign commercials.
He decided to skip the first four nominating contests, held in states where campaigns traditionally spend a year organizing supporters, to focus instead on the delegate-rich primaries that take place beginning on Super Tuesday, March 3. His rivals, meanwhile, have been torn between attacking him and battling one another in the early-state contests.
Mr. Bloomberg, who has emerged in recent years as a leading financial benefactor for Democratic candidates and some liberal causes, such as gun control and environmental protection, entered politics as a Republican when he first ran for mayor in 2001. He endorsed President George W. Bush and spoke at the 2004 Republican National Convention.
He has backed other Republicans as well, including Senator Scott Brown of Massachusetts, who was ousted by Ms. Warren in 2012, and Senator Pat Toomey of Pennsylvania, a gun control ally, in 2016.
Rebecca R. Ruiz contributed reporting from Las Vegas, and Giovanni Russonello from Washington.