Barack Obama will top the bill at a Biden campaign fundraiser in the spring. 

The event, reported by NBC, is the latest sign of Obama's growing involvement in Biden's troubled re-election bid.

The event will bring together the three most recent Democratic presidents - Obama, Biden, and Bill Clinton - in a show of force by the anti-Trump establishment.

Obama ready to jump into 2024

The plans reflect the extent to which Democrats fear Biden is vulnerable, and in need of Obama's charisma to carry him through a long election year.

Sources said the plan is for the event to happen in March or April.

Democrats are desperate to drum up some enthusiasm for 80-year-old Biden, who is faced with worse approval ratings than either Obama or Clinton had at this time in their presidencies.

"There is real focus and urgency around making sure we beat Trump,” a Biden adviser said. “Everyone is all in. And this kind of event early on is just the latest demonstration of that.”

According to a string of reports in the liberal media, Obama and those close to him are concerned about Donald Trump's momentum - and Obama has privately counseled his former vice president to retool his campaign.

Trump has gained the upper hand in the polls, with discontent over the direction of the country and its economy running high.

Democrats have framed the 2024 election in sweeping terms as a test of American "democracy," painting Trump as an existential threat to America's system of government.

Biden shows signs of vulnerability

Trump and his defenders readily fire back that efforts to frustrate Trump's campaign with lawfare - including an effort to take him off the ballot - are anything but democratic.

In any case, Trump is leading Biden by four points in the RealClearPolitics average of polls, a clear sign that Biden's rhetoric isn't having its intended effect.

Biden's low-velocity campaign has already raised eyebrows after he previously spent the 2020 election holed up in his basement in Delaware. But officials told NBC that Biden plans to pick up the pace very soon.

“It’s going to be very aggressive,” a White House official said.

The 2024 election is shaping up to be a close fight - much closer than Obama wants it to be.