The 49-year-old broke a barrier in 2021 when he was sworn in to fill Kamala Harris’ seat after she became vice president. His appointment by Gov. Gavin Newsom was celebrated as providing representation for the large and growing Latino population in the state. On Tuesday, voters chose Padilla to complete Harris’ term through Jan. 3 as well as for a full six-year term of his own. In both elections, he defeated GOP attorney Mark Meuser.

“We have a hell of a fight ahead of us, and I’m heading back to the Senate ready to help lead that fight,” Padilla said at a Democratic election party at the Hollywood Palladium, as it was starting to fill up with supporters. He pledged to prioritize job creation, climate change, immigration reform, reproductive rights and the protection of Social Security and Medicare.

Padilla’s election, which had been widely expected, was a bright spot for Democrats in a midterm election in which the party was fighting for control of the House of Representatives — and in which control of the Senate was also in play.

The party in control of the White House almost always loses congressional seats in the first midterm election during its term. President Biden faced headwinds because of his lackluster approval ratings, combined with voter discontent fueled by inflation.

But even in tough years for Democrats, California can be an outlier, with red waves stopping at the state’s border.

In 2010, when tea party-stoked Republicans picked up more than 60 House seats in races across the nation — the largest gain in more than half a century — California Democrats ran the table in statewide races and didn’t lose a single seat in the state’s congressional delegation.

But the party’s prospects in Congress are uncertain, and if Republicans win back the House, the results in several California races will shape the margin of power.

California, which has the largest congressional delegation of any state, has seen dizzying gyrations in recent elections. In 2018, Democrats flipped seven GOP seats. Two years later, Republicans won three Democratic districts and narrowly held on to one they seized in a special election earlier in the year.

While the state lost a congressional seat for the first time in its history after the 2020 census, Democrats remained optimistic about their prospects because many newly drawn congressional districts appeared to favor their party. GOP incumbent Reps. Mike Garcia of Santa Clarita, David Valadao of Hanford and Michelle Steel of Seal Beach were drawn into more competitive districts.

But as economic woes dominated the discourse, Democrats started to worry about their ability to flip those districts — and to protect some of their own incumbents, such as Reps. Katie Porter of Irvine and Mike Levin of San Juan Capistrano.

Races in five of the state’s districts were rated toss-ups by the nonpartisan Cook Political Report, and another six were deemed competitive. In several of those, Democrats have a substantial edge in voter registration; in some, Biden won by double digits in 2020.

Four congressional districts that include parts of Orange County, a onetime conservative bastion that has become purple, are among those in play.

GOP elected officials and supporters gathered for a celebration at a Newport Beach nightclub and watched East Coast results roll in on television. Steel thanked campaign volunteers who she said knocked on more than 195,000 doors. She was trailing in very early returns, but she told the crowd the race looked “really good.”

Congressional candidate Scott Baugh speaks to a crowd of California Republicans at an election night party in Newport Beach.

(Hannah Fry / Los Angeles Times)

“Some people get discouraged, but please don’t be,” she told hundreds of attendees milling around cocktail tables dotted with small red elephant signs that said “Proud Republican.” “In 2020, first ballots came in and I was 26,000 down. No one is down that much today.”

Incumbent Rep. Young Kim spoke with a tone of measured optimism, noting that Republican candidates across the state had “worked hard” to sway the balance of power in Congress. “I think we have a great chance of hopefully picking up a couple more seats,” she said.

Rep. Young Kim addresses a crowd of Republican candidates and supporters during an election night party in Newport Beach.

(Hannah Fry / Los Angeles Times)

Former GOP state lawmaker Scott Baugh added that early returns in California favor Democrats, but said he expects the tide to turn as election day ballots are counted. “There’s a lot of victories along the way. Just hang tight,” said Baugh, who ran against Porter. “I think about midnight you’re going to be really excited.”

In nearby Costa Mesa, Porter acknowledged the tightness of her race.

“You do not win races as a Democrat in Orange County without a few close election nights,” Porter told about 200 supporters gathered in a hotel ballroom, before turning to national results. “We’re winning some, we’re losing others.”

“No matter what the results show over the next few days … we won’t back down,” she pledged.

Kim’s challenger, Asif Mahmood, a Democratic physician, thanked supporters in a statement and told them he was watching race results with hope. “I am here to tell you whatever happens and whoever wins this election,” he said, “I believe in each and every one of you and your willingness to fight for what’s right.”

The weekend before the election, Padilla stumped for Mahmood, Porter and congressional hopeful Jay Chen, who challenged Steel in Orange County. The senator joined other statewide elected officials in Long Beach on Sunday to campaign for Proposition 1, the ballot measure that would codify abortion rights in the state Constitution.

Padilla was so confident that he didn’t campaign for himself or air a single general election ad. Democrats have a 23-percentage-point edge over Republicans in California voter registration.

Padilla and his two siblings were raised in Pacoima by their immigrant parents, a short-order line cook and a housekeeper. He said their efforts to keep him focused on education, volunteer work at their Catholic church and baseball kept him busy and out of trouble in a neighborhood that he described as being beset by drug dealing and prostitution.

He graduated from MIT and returned home to work in engineering. But his career plans changed because of his outrage over Proposition 187, the successful 1994 ballot measure that sought to deny many taxpayer-funded services to immigrants in the country illegally.

Padilla was part of a generation of young Latinos in Los Angeles spurred into politics by the proposition, which was later largely struck down by the courts as unconstitutional. He began by working on local Democratic campaigns.

Padilla was elected at the age of 26 to the Los Angeles City Council in 1999 and became council president two years later. He was elected to the state Senate in 2006.

Times staff writer Ben Oreskes contributed to this report .