Former U.S. Vice President Joe Biden, a potential 2020 Democratic presidential candidate, speaks at a rally with striking Stop & Shop workers in Boston, Massachusetts, U.S., April 18, 2019. Brian Snyder | Reuters

As he geared up to announce his expected run for the White House in 2020, former Vice President Joe Biden was working the phones as recently as a few days ago to line up fundraising support. One of his lead backers, former Pennsylvania Gov. Ed Rendell, said he recently received a call from Comcast executive David Cohen about a potential Biden fundraiser at his home in Philadelphia. Then came the message from Biden himself late last week. Biden told Rendell "he was going to do it [run for president]. He was going to do it with all his energy and heart. He thinks it's the right thing to do and the right thing for the country," Rendell told CNBC in an interview. Biden will announce his candidacy through an online video Thursday and hold his first public event as a candidate Monday in Pittsburgh, according to a Biden aide who declined to be named. Biden represented Delaware in the U.S. Senate for more than three decades, but he routinely highlights his roots in the blue-collar Pennsylvania city of Scranton.

Rendell and Cohen have been making calls to potential donors to get them on board for what they hope will be one of Biden's first big-money fundraising events. So far, Rendell has called 20 financiers, and 18 have committed to coming to their event, he said. "Pretty much 80 percent of the Democratic fundraising establishment are pretty much all on board," said Rendell, who has known Biden for decades. Cohen is known to be a prolific fundraiser within the Democratic Party. In 2011, Barack Obama's reelection campaign raised $1.2 million through two Cohen fundraising events, The Washington Post reported at the time. The support from establishment Democrats such as Rendell, who backed Hillary Clinton in 2008 and 2016, and Cohen could be a boost for Biden, who is late to the fundraising game this cycle. The primary is already crowded, and some of his would-be rivals, such as South Bend, Indiana, Mayor Pete Buttigieg, have put together expansive bundler lists. President Donald Trump, meanwhile, has already brought in a load of cash. His campaign raised about $30 million in the first quarter. Some of Biden's closest advisors, including his foundation's vice chairman, Mark Angelson, have reached out to several Democratic fundraisers and donors — as well as people who have already committed to backing other primary contenders, according to people familiar with the deliberations.