The win came after a redistricting process that made the district more competitive. Under maps submitted by Gov. Tony Evers and approved by the Wisconsin Supreme Court, the 1st District moved from favoring Republicans by 14 percentage points to a six-point Republican lean, according to FiveThirtyEight. The new boundaries brought Beloit and parts of Whitewater and Milwaukee's suburbs into the district while removing some right-leaning rural areas.

Berman's victory was part of a broader wave of Democratic wins across the country. But holding the seat in 2028 will require a different kind of campaign, said Mordecai Lee, a professor emeritus of political science at UW-Milwaukee.

"Voters in the southeastern Wisconsin district have shown they're comfortable voting for Democrats and Republicans," Lee said. The key to defending or reclaiming the district, he added, is who can best communicate with voters there.

Lee predicted Steil will "probably do what every self-respecting politician would do: regain his honor by running again and recapturing his seat." But he also floated other possibilities, including an appointment in President Donald Trump's administration that would keep Steil visible in Wisconsin, or a job in the artificial intelligence and cybersecurity sectors, which Lee said supported Steil and might reward him with a position.

"Doing that would also be a signal to other like-minded, current politicians that this industry takes care of its own," Lee said.

If Steil remains in politics, he could set his sights on a U.S. Senate seat should Ron Johnson retire when his term ends in 2028, said Aaron Weinschenk, a political science professor at UW-Green Bay.

"Obviously we don't know if Ron Johnson will run for another term (although I think he's considering retirement), but someone like Steil who previously served in the House could be a possible candidate," Weinschenk said.

Steil's campaign did not respond to requests for comment.

For Berman, the path to reelection may depend on how he positions himself. Lee said Berman should have already begun his reelection campaign and should avoid emphasizing his party affiliation, instead presenting himself as a representative of the entire district.

Weinschenk said the political environment in 2028 is difficult to predict. "A lot can change in two years," he said. "If Democrats are responsive to the issues that Americans are concerned with, the political environment could be favorable for Democrats in 2028. If they have a harder time addressing the issues on people's minds, then the environment might be more difficult."

The district's boundaries could also shift again before 2028, as at least one lawsuit seeking another round of redistricting remains active.

History offers a cautionary tale for Berman. In 1974, Father Robert Cornell, a Catholic priest and political science professor, rode the anti-Republican wave after Watergate to win in the 8th Congressional District, a right-leaning area in northeastern Wisconsin. Cornell won again in 1976 but lost his bid for a third term in 1978.

For now, Berman's upset has given Democrats a rare foothold in a district that had been reliably red for a generation. Whether it becomes a lasting gain or a temporary one will depend on the choices both parties make in the next two years.