Does Kamala Harris already have a challenger? Top senator weighs giving outgoing President Biden's successor a run for her money in 2024 election

Independent Senator Joe Manchin is considering returning to the Democratic party and jumping in the presidential race now that President Joe Biden has announced he will not seek reelection. 

The West Virginia Senator had previously been floated as a potential unity candidate during the primary season but declined to run.

At the end of May, Manchin left the Democratic party after decades in office as a Democrat and registered as an Independent. 

But Manchin is now considering reversing course and re-registering as a Democrat to run for president, a source confirmed to DailyMail.com.

It comes after Biden announced Sunday afternoon he would not seek reelection and endorsed Vice President  Kamala Harris for the nomination. Harris then announced she was running for the Democratic presidential nomination but it is not a closed deal. 

Some Democratic officials immediately jumped to endorse her but others held off and called for the Democratic process to play itself out as delegates must officially select their nominee next month. 

Earlier on Sunday, Manchin joined the growing chorus of elected officials calling on Biden to step aside. 

  'I came to the decision with a heavy heart that I think it’s time to pass the torch to a new generation,' Manchin said in a series of Sunday show interviews. 

He has long warned that he believes Donald Trump is a threat to democracy, but he had also expressed concerns over the president's health. 

Manchin has long gone back and forth between being a thorn in Biden's side and an ally. He helped Democrats pass some of their biggest pieces of legislation under Biden over the past three years while extracting key demands that removed some components that had been top priorities for progressives. 

Jumping in the Democratic race for president and challenging Biden's endorsed candidate would be one more needle in President Biden's side from the West Virginia moderate.

When Manchin exited the Democratic party less than two months ago, he said he was making the decision to 'stay true to myself and remain committed to put the country before party.'

Despite the party registration change, Manchin has continued to caucus with Democrats on Capitol Hill. 

Manchin announced last fall that he would not seek reelection as the senator from West Virginia in the increasingly red state. It is expected the Senate seat will flip to red this fall with Republican Governor Jim Justice as the West Virginia Senate nominee. 

Other Democrats who have been seen as potential replacements as the Democratic presidential nominee including Governor Josh Shapiro, Governor Gavin Newsom and Governor Roy Cooper have all come out in support of Harris at the top of the ticket.