Professor Katherine Porter.

Talk about a rollercoaster.

Nine days after University of California, Irvine School of Law professor Katie Porter seemingly lost her bid to unseat Orange County Congresswoman Mimi Walters, she was declared the winner of California's 45th Congressional District seat.

The Associated Press called the race for Porter on Thursday evening after the slow provisional and mail–in ballot tally in Orange County placed her with more than 6,000 votes over two-term Republican incumbent Walters. Initial vote counts on Election Day placed Walters ahead slightly.

“As your representative I will work to bring accountability back to Washington—to fight to protect our health care, for a clean and safe environment for our communities, and for fair taxation so that everyone pays their fair share,” Porter said after AP named her the winner.

Porter wasted no time getting into the Washington swing, and posted a video to Twitter on Thursday showing her outside the U.S. Capitol in the rain.

The race between Porter—a protégé of U.S. Sen. Elizabeth Warren who ran on a progressive platform—and Walters garnered national attention and was seen a proxy for Democrats' ambitions to flip traditionally Republican districts in affluent suburbs. Hillary Clinton won the 45th District in 2016, though it has long been a conservative stronghold. The race was an expensive one, with $27 million spent by both campaigns and outside groups. It was the 10th costliest house race in the country.

Porter's path to Washington was a slog. She narrowly won a hard-fought primary that pitted her against UC Irvine law colleague David Min and three other challengers. The primary soured a once-friendly relationship between the two law professors. Porter, a single mother of three, accused Min of dragging details of her divorce into the spotlight—a charge Min denied.

But Min offered words of praise for Porter on Friday on Facebook.

“Congratulations to Representative-elect Katie Porter and her team for an incredible campaign that did what many people thought was the impossible—unseating Mimi Walters here in the heart of Orange County, an area that Ronald Reagan once described as the land where 'all the good Republicans go to die,'” Min wrote.

Walters also conceded the race Friday and offered congratulations to Porter.

“New opportunities and challenges lie ahead and I will forever be grateful for the opportunity to serve in the People's House,” she wrote on Facebook.

Porter has taught at Irvine's law school since 2011. Prior to that, she was on the faculty at the University of Iowa College of Law for five years, and was a visiting professor at Harvard Law School; the University of California, Berkeley School of Law; and the University of Illinois College of Law.

Read more: Bruising Primary Drives Wedge Between UC Irvine Law Prof Candidates