Former Secretary of State John Kerry announced his support for former Vice President Joe Biden on Thursday. The longtime senator who was tapped by President Obama to serve as secretary of state in his second term, Kerry was the unsuccessful Democratic nominee for president in 2004.

"I believe Joe Biden is the President our country desperately needs right now, not because I've known Joe so long, but because I know Joe so well. I've never before seen the world more in need of someone who on day one can begin the incredibly hard work of putting back together the world Donald Trump has smashed apart," Kerry said in a press release.

He added that Biden is "uniquely the person running for president who can beat Donald Trump," reiterating an argument from the campaign that Biden is the most likely to win in the general election. Kerry, who served with Biden in the Senate for over two decades, also said that he did not "endorse lightly."

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"Joe will defeat Donald Trump next November. He's the candidate with the wisdom and standing to fix what Trump has broken, to restore our place in the world, and improve the lives of working people here at home," Kerry said.

While the high-profile endorsement could help showcase the argument for Biden's electability, it could also further cement Biden's status among progressive voters as an establishment candidate who represents a vision of the Democratic Party that is no longer relevant.

Kerry will join Biden for his "No Malarkey" bus tour in Iowa on Friday, and will travel with Biden to New Hampshire on Sunday. Kerry won the Iowa caucus and the New Hampshire primary in 2004.

Kerry's endorsement was first reported by the Washington Post's Dan Balz.