Within hours of former Vice President Joseph R. Biden’s long-awaited announcement early Thursday that he would wage his third presidential campaign, he had already received endorsements from a raft of members of Congress.

By early afternoon, nods had come from Sens. Bob Casey Jr. of Pennsylvania and Doug Jones of Alabama, as well as Reps. Tom Suozzi of New York and Matt Cartwright of Pennsylvania.  

Biden, who represented Delaware in the Senate for more than 30 years, also collected endorsements from the state’s entire congressional delegation: Sens. Chris Coons and Thomas R. Carper and Rep. Lisa Blunt Rochester. The endorsements made reference to decades of friendship and work alongside Biden, who won his first Senate election in 1972. 

Carper referred to a relationship that dated back to 1982, when he said Biden “first encouraged” him to run for Congress, and was deepened 18 years later when Biden encouraged him to run for the Senate. 

“For months, I have encouraged him to seek the highest office in our land and, today, I could not be more proud to endorse my friend Joe as he launches his campaign to be the next President of the United States,” he wrote. 

Casey called him “my friend,” in a tweet. 

I am proud to endorse my friend, Joe Biden, for President https://t.co/ZWTlwJaQ59

— Bob Casey Jr. (@Bob_Casey) April 25, 2019

Jones and Biden are friends, and Biden was one of the few Democrats with a national profile who went to Alabama to campaign for Jones when he won a special election there in 2018. He referred to Biden’s “ability to bring people together,” in a tweet. 

The quality that makes Joe stand out is his ability to bring people together to find common ground while standing up for what he believes is right. We need to listen to each other & get things done for working people. Joe can, and will, do that. That’s why I support Joe Biden. https://t.co/vxnLQu0XDZ

— Doug Jones (@DougJones) April 25, 2019

Those bonds, along with Biden’s uncommon biography, have placed him as a front-runner and a leader in public opinion polls, even though he is late to enter a crowded race and has already stirred speculation about whether he is struggling to meet his opponents’ fundraising totals.

But the rush to Biden’s side from Capitol Hill is likely to raise tensions among progressive leaders calling for fresh and diverse party leadership. They have complained that the white, male candidates are getting outsize attention and support in a historically diverse field of Democratic contenders.

That tension was already evident Thursday morning in a statement from the progressive group Justice Democrats opposing Biden’s nomination.

“The old guard of the Democratic Party failed to stop Trump, and they can’t be counted on to lead the fight against his divide-and-conquer politics today,” a statement from the group read. “The party needs new leadership with a bold vision capable of energizing voters in the Democratic base who stayed home in 2016.”

“While we’re going to support the Democratic nominee, we can’t let a so-called ‘centrist’ like Joe Biden divide the Democratic Party and turn it into the party of ‘No, we can’t.’”

Justice Democrats is a political action committee aligned with Rep. Alexandria Ocasio-Cortez that has worked to reshape the party partly through primary challenges against moderate Democrats.

Biden brings the number of Democratic hopefuls to 20 people, half of whom are current or past members of Congress.

His seven endorsements from Capitol Hill within hours of his announcement were a sign that he will have strong support from the party’s establishment, and he already had more Senate supporters than anyone in the field.

Only Sen. Cory Booker has collected more total — with backing from 11 House members and his New Jersey Senate colleague Robert Menendez since he entered the race in February, according to a Roll Call tally.

California Sen. Kamala Harris, who also announced her campaign in February, has five endorsements from House members. Massachusetts Sen. Elizabeth Warren and former Texas Rep. Beto O’Rourke each have four. Warren’s total includes one Senate endorsement, from her Massachusetts colleague Edward J. Markey.