U.S. Senator Joe Manchin, a maverick Democrat who has often bucked party leadership, told a radio station in his home state of West Virginia on Thursday that he is "thinking seriously" about leaving the party.

"I'm not a Washington Democrat," Manchin said in the interview on Talkline with Hoppy Kercheval, a West Virginia Metro News show. "I've been thinking seriously about that (becoming an independent) for quite some time."

Manchin and Democratic-turned-independent colleague Senator Kyrsten Sinema have been thorns in top Senate Democrat Chuck Schumer's side since the party won its majority in 2020. Democrats hold a 51-49 majority, including three independents who caucus with them.

Last month Manchin further stirred Democratic concerns with an appearance in the early-voting state of New Hampshire with the "No Labels" group, where he mulled starting a third-party presidential campaign in 2024, challenging Democratic President Joe Biden. Having a third-party candidate would "threaten" the two major political parties, Manchin said.

Manchin has used his influence to block legislation that he opposes - including expanding voting rights protections and child tax credits - and to ensure passage of bills he supports, such as a major tax and climate law that passed last summer.

He faces a tough re-election bid next year in Republican-leaning West Virginia, which former President Donald Trump won by almost 39 percentage points in 2020. Manchin has not yet said if he will seek re-election, but he would face an even steeper road if he spurned his party and the fundraising support it can provide.

West Virginia Governor Jim Justice, a former Democrat-turned Republican, began his campaign in April for the Republican nomination to seek Manchin's seat.

Manchin, a popular former governor who was first elected to the U.S. Senate in 2010, has kept his seat in part by maintaining a reputation as a rare conservative Democrat in Washington.