Joe Biden may have been President Barack Obama’s vice president, but that is not stopping other candidates in the field from brandishing their own connections to the former president as they try to win over Democratic primary voters.

With polls showing Democratic voters longing for a return to Obama’s two terms in the White House, many of the 22 candidates running for president are scrambling to hire his former staffers, talking up their relationships with him and presenting themselves as defenders of his policies.

When former Congressman Beto O’Rourke announced a key new hire last week, his campaign stressed that new senior advisor Jeff Berman had been a big part of Obama’s 2008 election. And for good measure, they reminded reporters that his campaign manager Jen O’Malley Dillon was a former deputy campaign manager for Obama in 2012.

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Other candidates have also put a premium on hiring Obama alums, as they are called in Democratic circles. Democrat Pete Buttigieg, the mayor of South Bend, Indiana, hired two top staffers who played key roles in Obama’s 2012 re-election campaign. And U.S. Sen. Elizabeth Warren early on added key former Obama staffers to her campaign.

On the stump, former San Antonio Mayor Julián Castro talks up his tenure as Obama’s Secretary of Housing and Urban Development — the only former Obama cabinet official running so far. He often recounts how he was at a Panda Express drive-thru in his hometown when Obama called to offer him the position at HUD.

It happened on April 16, 2014, Castro said in a campaign stop in New York. “I remember the date because it's not every day that you get a call from the president asking you if you want a job.”

And then there is Biden. He mentioned “Barack” five times in a 20-minute span in a speech in New Hampshire on Tuesday. In a digital ad, he has an Obama voice-over for 2 minutes and 45 seconds. The audio came from when Obama presented Biden with the Presidential Medal of Freedom in 2017.

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Polling shows why candidates want voters to see their ties to Obama: 97 percent of Democratic voters say they have a favorable view of the former president in one CNN Poll. And 72 percent of New Hampshire respondents in a Monmouth University poll said it was “very important” or “somewhat important” for the eventual Democratic nominee to build on Obama’s legacy.

But while Obama has met with many of the primary contenders in private meetings over the last several months, but hasn’t picked a favorite so far.

“President Obama wants to help Democrats win, and that is why he has been happy to speak privately with candidates and potential candidates seeking his guidance on the best way to lead the country,” said Katie Hill, the former president's communications director.

Even after Biden jumped in the race, Obama praised Biden but stopped well short of endorsing him.

“I asked President Obama not to endorse,” Biden said after announcing his campaign in late April. “Whoever wins this nomination should win it on their own merits.”

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But even without the endorsement, Biden is clearly getting a boost in the polls due to his tenure as Obama’s running mate, Texas Democratic political strategist Colin Strother said.

“I believe a lot of that support is based on Obama nostalgia,” said Strother.

The poll of New Hampshire voters seems to support that theory. Among those who said Obama’s legacy is very important in picking among the 23 candidates running for president, Biden was the choice of 39 percent. No other candidate had more than 15 percent.

Strother agrees with many analysts, however, in predicting that other candidates will be able to win some of those voters back.

“I love Joe Biden,” said Nate Lerner, of New York City who worked on Obama’s campaign in 2012 but was part of a Draft Beto campaign to urge O’Rourke to get into the race. “But we were attracted to Obama because he was a candidate who promised hope and inspired change.”

Biden doesn’t have that same calling card, Lerner said, after nearly 50 years in an out of Washington, D.C.

Biden has pulled Obama alums to fill out his campaign, too. He made Greg Schultz his campaign manager. Schultz was Obama’s state director in Ohio. He’s also made Pete Kavanaugh, who was Obama’s New Hampshire state director, his deputy campaign manager.

Reaching out to the Obama world also means trying to break into the financial circles that propelled Obama to record fundraising in both of his campaigns for president. According to a Washington Post report, few of Obama’s major donors have picked a candidate yet for 2020. The Post’s analysis showed just 1 in 10 of Obama’s 1,330 major donors had given over $2,700 to any of the 2020 candidates.

O’Rourke is making a play for those donors. On Tuesday he was in New York City meeting one-on-one with Robert Wolf, a major Obama fundraiser and former economic adviser to the president. O’Rourke held a fundraiser the night before in NYC.

And on June 10, O’Rourke is in Chicago for another major fundraiser loaded with former Obama donors and officials, according to Politico. That fundraiser is being hosted by Louis Susman, former ambassador to the United Kingdom under Obama and Austan Goolsbee, who led the Council of Economic Advisers under Obama.