Bernie Sanders’ presidential campaign released a new ad on Wednesday touting his relationship with former President Barack Obama, a day after Joe Biden, who served as Obama’s vice president, surged in the Democratic primary race with strong Super Tuesday results.

“Bernie is somebody who has a virtue of saying exactly what he believes, great authenticity, great passion and is fearless. Bernie served on the veterans committee and got bills done,” Obama says in the ad over photos of Sanders walking beside him at the White House.

“I think people are ready for a call to action. They want honest leadership who cares about them. They want somebody who’s going to fight for them. And they will find it in Bernie,” Obama says later in the ad. “That’s right, feel the Bern.”

The ad, along with two others also launched on Wednesday, is set to air in states holding primary contests on March 10 and March 17, including Arizona, Florida, Idaho, Illinois, Michigan, Mississippi, Missouri, Ohio and Washington, Sanders’ campaign said in a statement.

The release of the Obama-centric ad follows Biden’s massive comeback in the Democratic primary. Initial results projected Biden winning at least nine of the 14 states up for grabs on Tuesday, including Massachusetts, Minnesota, Oklahoma and Texas, and overtaking Sanders in overall delegates.

Sanders, however, won California ― the state with the most delegates up for grabs ― as well as Colorado, Utah and his home state of Vermont.

After disappointing showings in the first few primary contests, Biden now shares the top of the Democratic pack with Sanders, thanks to a landslide victory in South Carolina and a critical injection of moderate support from 2020 dropouts Pete Buttigieg, Sen. Amy Klobuchar (D-Minn.) and Beto O’Rourke ahead of Super Tuesday. Billionaire Mike Bloomberg quit the race Wednesday and joined Biden’s endorsers.

Sanders has been at times critical of the Obama administration, including its reluctance to prosecute Wall Street executives after the financial crisis of 2008. But with the new ad, the progressive senator, who has urged a “political revolution” to disarm the “corporate wing” of the Democratic Party, is likely trying to win the support of moderates, including some of Biden’s supporters.

Obama, who hasn’t yet endorsed a 2020 candidate, has reportedly told members of his inner circle that he does not want Sanders to win the party’s nomination.

In response to Sanders’ new ad, Andrew Bates, a spokesman for Biden’s campaign, told HuffPost in a statement that there’s “no substitute for genuinely having the back of the best president of our lifetimes.”

“Barack Obama chose Vice President Biden to be his partner over 8 years in the White House, entrusting him with managing the stimulus that saved our economy from a depression, obtaining the deciding vote for the Affordable Care Act, and countless national security priorities,” Bates said.

“By contrast, Senator Sanders explored a primary challenge to President Obama, who he compared to a ‘moderate Republican’ and said was not a ‘progressive,’” Bates continued.

The Sanders campaign has denied that it “crossed his mind to challenge Obama” in 2012.

Amanda Terkel contributed reporting.