FULLERTON, Calif. — Orange County is a microcosm of the nationwide battle for control of the U.S. House.

In 2018, Democrats snatched four congressional seats from Republicans there, turning the delegation completely blue. But last year, Republicans took two of them back. Now both parties are focused on winning here next year.

Rep. Young Kim, R-La Habra, met with the Fullerton police chief last month to discuss using an old space near Providence St. Jude Medical Center for a new home base on a multi-city project that works to combat homelessness. It would refurbish a space for homeless outreach works and liaison officers to meet and work on their collaborative effort to fight crime in the district. This effort is just one of Kim's several local projects she's asked Congress to fund in her first year in office.

Kim ran in 2018 and lost. She ran again last year and won by about 4,000 votes. 

"I didn't give up because I knew, with the right message, and staying connected and being grounded in the communities, I knew I can get to the hearts of the people, not just the voters, but the constituents and the residents," she said.

Kim is one of four Republican congressional candidates in California who won last year in a previously Democratic district. Two of those candidates, including Kim, unseated Democrats in Orange County. Their victories marked a stunning reversal for Democrats who steadily made inroads in the county after decades of Republican domination.

"While the Democrats may have a little bit of a registration advantage, I don't think the county has changed much. We just need to make sure that there are more of us out there talking about what we believe in our conservative values," Kim said.

Since her upset victory, Kim has followed a careful strategy designed to appeal to swing voters. Hours after the Jan 6. riot at the Capitol, she was the only California Republican to certify Joe Biden's election as president. She joined the Problem Solvers Caucus, a bipartisan group of House members that seeks common ground on key policy issues. And she sponsored bills that won enough Democratic support to pass the House.

"For me, representing a purple district like the 39th, where we have one-third Asians, one-third Hispanic, one-third Caucasians, they are looking for someone who is independent and who can bring across the board, you know, leadership that doesn't always stick too far right, far left," Kim said. "Someone who works on the policies because it's the right thing to do."

Rep. Mike Levin, D-Carlsbad, is following a similar bipartisan playbook as a Democrat. He won the election in the blue wave of 2018 and held on last year.

"Having grown up in South Orange County, I was really excited when in 2018 all seven representatives from Orange County were all Democrats," Levin said. "The first time that's ever happened. And now, we still have a lot of work to do."

As a sign of his strategy, half of the bills Levin has introduced this year would help veterans, an issue that enjoys bipartisan support. He also avoids focusing on former President Donald Trump but has his work cut out for him. The National Republican Congressional Committee is making Levin a top target next year.

"I intend to make a difference for this community, and I can't worry about the former president, what he says, or what he writes, I have to focus on the residents of this district and what their needs and concerns are. That's what I've done. That's what I'll continue to do," Levin said.

Republicans need to flip just five Democratic seats next year to retake control of the House. The ability of Kim and Levin to defend their seats could determine whether that happens, which means Orange County is once again going to be an intense political battleground.

This story is Part 1 of the Battleground California political series titled "Orange County." Part 2 focuses on lawmakers who take an opposite tack, titled "Bold Swing Districts." Part 3 focuses on House Minority Leader Kevin McCarthy, titled "Race for Speaker."