Pennsylvania Sen. John Fetterman on Saturday mistakenly called himself a “lifelong Republican,” an awkward slip from the Democrat whose moderate positions have fueled months of speculation that he could eventually leave the party.

Fetterman, 57, quickly joked about the misstatement during a Texas Tribune Festival appearance. Moderator Major Garrett reminded him that he was, in fact, a Democrat.

The senator, who has repeatedly been asked whether he might abandon the Democratic Party, immediately recognized that the gaffe could attract widespread attention.

“I guarantee you, that’s gonna break through,” Fetterman said.

Fetterman has kept the question of his political future alive for months. In a May Washington Post op-ed, he wrote that he would be a “terrible Republican who still votes overwhelmingly with Democrats.”

He also left open the possibility of switching parties if Democrats became the “anti-Israel party.”

Many of Fetterman’s positions remain closely aligned with the Democratic platform, including support for abortion and LGBTQ rights, expanded healthcare and a higher minimum wage. However, he has sharply clashed with the party’s increasingly influential far-left wing, particularly over Israel.

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His recent appearances alongside Republicans have added to the uncertainty among his constituents.

Earlier this month, Fetterman appeared by video at the Republican midterm convention and pledged to “work with President Trump.”

Following backlash over the appearance, Fetterman told reporters on Capitol Hill that he was “not going to be a Republican.”

“Why can’t you guys just wait till the midterms? And if I turn Republican, then I’ll be a liar. … Chill,” he said.

Even so, Fetterman has broken with Democrats on several prominent issues, including votes against Iran war-powers resolutions and efforts to cut off U.S. aid to Israel.

At the festival in Austin, he again pushed back on the idea that a Republican future was entirely impossible, saying he “has no path as a Republican” and that “that’s a fact.”

Fetterman nevertheless acknowledged that the post-midterm political landscape could place him in a pivotal role. He discussed the possibility of Democrats retaking control of the Senate and his potential position as the 51st vote.

“Let’s revisit this after the midterms, and let’s see what happens, you know, if I happen to be 51. I don’t know,” Fetterman said.