WASHINGTON ― As President Joe Biden works to unite all factions of the Democratic Party, his campaign will get an assist Thursday night from two former presidents who know a thing or two about winning reelection and rallying the base.

Barack Obama and Bill Clinton will co-headline a high-dollar fundraiser at New York's Radio City Musical Hall that the Biden campaign said will raise at least $25 million − easily the most lucrative fundraiser of the election cycle. More than 5,000 supporters are expected at the sold-out event.

Yet perhaps even more critical than the mountain of cash, the rare showing of three Democratic presidents presents a united front to help Biden bring together a Democratic coalition that's shown signs of splintering.

Despite easily securing the Democratic nomination, polling has shown Biden is underperforming among Black and Latino voters compared to the 2020 election, while some within the progressive wing of the party have held off support due to his support of Israel's war in the Gaza Strip.

"The fact is that Joe Biden is still pulling the Democratic coalition back together," Donna Brazile, former chairwoman of the Democratic National Committee, told USA Today. "And with the help of Bill Clinton and Barack Obama and many others, this will make his task much easier. This is all about unifying the party."

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For Biden, being joined by his two most recent Democratic predecessors is also a luxury that presumptive Republican nominee Donald Trump lacks, having alienated himself from the Republican Party's old guard, including former President George W. Bush, the only living former GOP president.

Obama, who remains an icon among Democrats more than seven years after leaving the White House, has privately expressed alarm about the possibility of a second Trump presidency and is engaged directly with Biden's campaign.

The New York Times reported Wednesday that Obama, who tapped Biden as his vice president during his 2008 run, speaks regularly by phone with Jeff Zients, Biden's chief of staff, and other senior Biden campaign aides.

"Given the stakes of this election, President Obama will do all he can to support President Biden’s re-election," said Eric Schultz, a senior advisor for Obama. "In fact, he looks forward to helping Democrats, up and down the ballot, make the case to voters this fall. Our strategy will be based on driving impact, especially where and when his voice can help move the needle."

Both Obama and Clinton hit the campaign trail in Biden's 2020 bid, and Thursday's fundraiser is expected to be the first of many more stump speeches ahead of the 2024 election.

'Red flags' about Trump from the president's club

Obama's role in the 2024 contest has been the source of constant chatter and news reports, especially given his popularity relative to Biden within the party.

Democratic operatives, whether with the White House or Biden campaign, are quick to smother any speculated rifts between the two men or disagreement between their respective camps in the party's universe.

Instead, they seek to spotlight Obama as an advisor-in-chief for Biden and a younger generation of candidates, who connects dots from the 2012 campaign to today while keenly eyeing larger structural barriers − a fractured media landscape and immovable Trump supporters − that all Democrats will face this year.

"I see it as one team learning," a person close to Obama, who is familiar with his thinking, told USA Today. "It's very much, 'how can we all take these lessons and keep pushing this ball?'"

Obama has lent his hand to help emphasize the impact of the Affordable Care Act, his signature achievement as president, as part of the campaign's messaging. Obama joined Biden in a video last week to mark the 14th anniversary of the ACA, which Trump has long threatened to repeal.

“In your early 20s? You might not know that the Affordable Care Act is the reason you can stay on your parents’ health care plan until you’re 26,” Obama said in a post Tuesday on X, formerly known as Twitter.  

“Before the ACA, health care companies could kick you off earlier – sometimes right after college. It’s another reason why we need to keep building on the ACA – not repeal it. Because health care isn’t a privilege. It’s a right.”

The Biden fundraiser will also serve as a reminder for voters of how seriously the previous White House occupants view a potential second Trump presidency.

"President Obama once said to me that every president is a reflection of the previous president, and he’s right. Trump was the complete opposite of Obama, and Biden is the complete opposite of Trump," said Democratic strategist Jim Messina.

"Being the President of the United States means you’re part of a small club; there is no other group of people whose red flags about the direct threat of Donald Trump should be taken more seriously."

White House press secretary Karine Jean-Pierre echoed those sentiments during a press briefing Wednesday. She said Biden, Obama and Clinton "agree overwhelmingly" on how to continue the nation's economic gains and protect "our critical freedoms," singling out reproductive rights and American democracy.

"We understand the importance of the three of them being together," Jean-Pierre said.

Biden turning a corner amid troubling Dem numbers?

The fundraiser, which comes as Biden has already significantly outraised Trump in campaign money for the general election, will be a star-studded affair.

Stephen Colbert, host of CBS' "The Late Show with Stephen Colbert," will moderate an "armchair conversation" with Biden, Obama and Clinton. Actress Mindy Kaling, star of the hit Fox romantic comedy "The Mindy Project" will host the program, which will feature musical guests Lizzo, Queen Latifah, Ben Platt, Cynthia Erivo, and Lea Michele.

A photograph with all three presidents will cost $100,000 and up, NBC News reported, but the tickets to attend the program went for as little as $250 each.

The fundraiser's $25 million haul is more than the $20 million Trump and the Republican National Committee raised in the entire month of February. It will add to Biden's campaign war chest of $155 million, the most ever for a Democratic candidate at this juncture of the race.

Democrats hope the presence of Obama and Clinton can also begin to help shore up support among key constituencies who are lagging for Biden.

A USA TODAY/Suffolk University poll taken March 8-11 found Biden is backed by 54% of registered Black voters, significantly less than the 87% of Black voters who voted for Biden in 2020. The poll found Trump leads Biden among Latino voters 35%-33% after Biden won 65% of Hispanic voters in 2020. Trump leads voters ages 18 to 34 − another plank of the Democratic base − 37%-31%, according to the poll.

Saddled by low approval and favorability ratings, Biden also faces a threat from third-party contenders − independent Robert F. Kennedy Jr., Green Party candidate Jill Stein and American philosopher Cornel West − who are vying for a mix of disgruntled Democrats, left-leaning voters and disaffected Americans.

Similar to the 2016 election, in which Trump defeated Democrat Hillary Clinton, this year's race features a significant share of "double hater" voters, between 15% and 20% of the electorate, who say they dislike both Trump and Biden.

There are signs, however, that Biden could be turning a corner in a rematch against Trump.

A Morning Consult/Bloomberg poll this week found Biden leading Trump nationally 44%-43. And the same pollster found Biden has made up ground in six battleground states that will likely decide the election. The poll found Biden ahead in Wisconsin by 1 point and tied with Trump in Pennsylvania and Michigan. And while Trump still leads in Nevada, Arizona, Georgia and North Carolina, the poll found the margin is now closer.

Brazile said she's confident the Democratic coalition is coming together, calling it a "slow process."

She noted Biden lacked a competitive Democratic primary opponent unlike Trump, who at one point faced half a dozen rivals in the GOP primary. "It's the most diverse coalition in American politics," Brazile said, pointing to young, minority, working-class and college-educated voters who the Biden campaign needs to unite.

"These voters have to be persuaded. The days of taking any group of Americans for granted, those days are over," she added.

"This is a very important time to remind voters that the Democratic Party led by Joe Biden has the backing of the former presidents, as well as the support of millions of Americans who would like to continue to see him finish the job."

Reach Joey Garrison on X, formerly Twitter, @joeygarrison and Phillip M. Bailey on X @phillipmbailey