Senator Joe Manchin III, Democrat of West Virginia, told a local news station on Thursday that he “would think very seriously” about leaving the Democratic Party and becoming an independent.

“I’ve been thinking about that for quite some time,” Mr. Manchin said in an interview on MetroNews’s “Talkline” show, adding: “The brand has become so bad, the D brand and R brand. In West Virginia, the D brand because it’s nationally bad. It’s not the Democrats in West Virginia. It’s the Democrats in Washington, or the Washington policies of the Democrats. You’ve heard me say a million times that I’m not a Washington Democrat.”

He said he had not made a decision yet — either about his party affiliation or about his electoral plans. He is up for re-election to the Senate next year in what, if he runs, promises to be a very difficult race, and he has flirted with running a third-party campaign for president.

Last month, he appeared at an event for the bipartisan group No Labels, which is considering fielding a third-party ticket in 2024 to the alarm of Democrats, who fear it would draw enough voters away from President Biden to ensure a Republican victory.

No third-party candidate has come close to being elected in modern times, and it was not clear in the MetroNews interview that Mr. Manchin himself thought such a candidacy was viable. He framed it instead as a way to “make a big, big splash and maybe bring the traditional parties, the Democratic and Republican Party, back to what they should be” — which, in his view, is “the middle.”

If Mr. Manchin did leave the Democratic Party, he would be the second senator to do so in a short span of time. Senator Kyrsten Sinema of Arizona, who was elected as a Democrat in 2018, became an independent at the end of last year. Like Mr. Manchin, she faces a difficult re-election campaign next year if she chooses to run in a three-way race against a Democrat and a Republican.