I remember the spring of 2001, working in my second role for my first employer (CNN). It was about six months after Democrats narrowed the GOP Senate majority by four seats, leaving Vice President Dick Cheney to break any 50-50 votes. It was also six months after Vermont Sen. Jim Jeffords was reelected as a Republican when he became an independent who caucused with the Democrats. It was the first time a party switch flipped control of the chamber.

Fetterman has been publicly toying with his own party switch, including comments to Semafor on July 30: “I don’t know if the Democratic Party is ‘big tent’ enough for proud, pro-Israel supporters that also strongly reject the warped mutation of” democratic socialists now rising in their ranks.

Even though Fetterman also recently reiterated that he wasn’t considering switching parties, the senator has voiced plenty of concern about his party. “I’ve described that if our party ever becomes … the anti-Israel party, you know, that’s when I would leave,” he said.

But it’s not hard to see the Democratic Party getting more critical of Israel, nor is it hard to see Fetterman ultimately making the jump. With his hooded sweatshirts and shorts, he’s already an unconventional senator. And when he realizes that his near-term electoral career is over (more on that in a moment), Fetterman could become even more of a wild card in his final two years before he leaves.

Fetterman’s independence has frustrated Democrats to the point that he probably can’t win a Democratic primary in 2028. And, if he switches parties, he probably can’t win a Republican primary either.

Fetterman is popular among Republicans because he’s a Democrat who criticizes Democrats. But that dynamic would change if he flips. Then he would be a liberal former Democrat trying to persuade GOP primary voters.

I think I’ve seen this movie recently. In Georgia, former Republican Lt. Gov. Geoff Duncan became a critic of President Donald Trump, spoke at the Democratic National Convention, became a CNN commentator and decided to switch parties. Then, when he ran for governor this cycle, Duncan received a whopping 7 percent in the Democratic primary.

We’ve even seen this dynamic in Pennsylvania going further back.

In 2009, longtime Republican Sen. Arlen Specter switched parties. “As the Republican Party has moved farther and farther to the right, I have found myself increasingly at odds with the Republican philosophy and more in line with the philosophy of the Democratic Party,” he said at the time. But when Specter ran for reelection in 2010, he lost the Democratic primary 54 to 46 percent to Joe Sestak.

“I’m not going to be a Republican,” Fetterman said on Meet the Press Now on July 29. “And I would just remind anybody that I’ve been very clear on that.” But I would remind everyone that politicians say things before they do the opposite thing, like when Illinois Sen. Barack Obama told Tim Russert in 2006 that he wouldn’t run for president and then announced his candidacy in 2007. And, like Jeffords, Fetterman would not need to become a Republican to swing the chamber.

Because the current fight for the Senate is so close, it’s prudent for anyone or any organization making plans based on which party controls the chamber to prepare for either scenario. But if Democrats gain control of the Senate by a single seat this November, it would be wise to hang on to those GOP majority plans for a little while even after the election.

Nathan L. Gonzales is a senior political analyst for the Public Affairs Council and editor of Inside Elections, a nonpartisan newsletter with a subscription package designed to boost PACs with a regular newsletter and exclusive conference call. You can also hear more on the Inside Elections Podcast. His email address is [email protected].