Sen. Elizabeth Warren (D., Mass.) Thursday night touted the come-from-behind finish of Katie Porter, her former student and protégé at Harvard law, after late-voting counting in Orange County handed her the victory over two-term Rep. Mimi Walters (R., Calif.).
"I'm proud of all our incredible incoming Democratic House members, but I'm ESPECIALLY proud of our newest: my former student & research partner @katieporteroc! WOO-HOO! You're going to be an AMAZING fighter for families in CA & across the country, Congresswoman-elect Porter," Warren tweeted.
The Associated Press called the election for Porter Thursday night after Orange County's tally found that Walters had dropped 6,203 behind her challenger after leading her by a more than 3,000 on election night.
Before the Porter win, the affluent district was considered a conservative stronghold, although a majority of voters in it favored Hillary Clinton over Donald Trump in 2016.
Porter tweeted out a video of herself standing outside the Capitol in the rain while attending freshmen orientation in Washington, D.C., Thursday.
"THURSDAY UPDATE: Thank you. I can't wait to get to work for Orange County and to stand with you 100% of the time!" she tweeted.
The loss in the 45th district marks the fifth of seven targeted California GOP House seats to fall to the Democrats with another adjacent district appearing poised to follow suit.
The updated vote count Thursday night also gave Democratic candidate Gil Cisneros a 941-vote lead in his neck-in-neck race against Republican Young Kim in the 39th district.
There are still tens of thousands of votes left to count, but each day Kim, who also held a lead against Cisneros on election night, has lost ground. If Kim ends up losing to Cisneros, it will be the first time Orange County has not had a Republican representing it in modern political history.
The only heavily targeted Republican who appears to have pulled off a midterm win is Rep. David Valadao (R., Calif.) who represents the GOP stronghold of Kings County in the agricultural-heavy Central Valley. On Thursday he added 228 votes to a 2,309-vote lead against Democrat TJ Cox.
Republicans now control the lowest number of California House seats in history—only nine of the 53 total.
Some Republicans have blamed the divisive politics of President Trump, especially when it comes to hardline immigration policies, as well as their inability to compete with the Democratic ground game.
Michael Bloomberg's Super PAC poured late money into several of the California races that were already awash in tens of millions from Democratic outside groups. Republicans PACs tried to compete but were outdone by Democratic volunteers and liberal organizations.
Tom Steyer's NextGen America exceeded its goal of registering 250,000 new voters, aged 18-35, across the country, concentrating on students near key universities and colleges. The effort likely helped Porter, a UC Irvine professor, because the campus youth vote this year was 10 times the 2014 turnout, according to data from the Center for Information and Research on Civic Learning and Engagement.
Shawn Steel, a former California Republican Party chair, says Trump is not to blame for the disappointing losses in California. Instead, he says the Democratic Party is dominating the political fundraising landscape and ground-game organization.
"To blame the president is to remain in denial about the real causes of Republicans' staggering setbacks," he wrote in a piece in the Washington Examiner Wednesday.
In the 39th district, Kim was outspent by a five-to-one ratio, against a multi-millionaire lottery winner who contributed $9 million to his own campaign.
"In the 25th Congressional District, Katie Hill defeated incumbent GOP Rep. Steve Knight with the help of $4.5 million from billionaire Michael Bloomberg's super PAC," he wrote.
He also cited Steyer's ground game, noting that the billionaire environmentalist spent $3.8 million on youth voter registration in California alone.
"In a pre-election memo, Steyer's NextGen America detailed how 68 staff members recruited nearly a thousand volunteers to register more than 28,000 youth voters in a half-dozen targeted California congressional seats," Steel wrote.