Republican Rep. Dan Lungren lost his re-election bid to Democratic challenger Ami Bera on Thursday in one of California's most hotly contested congressional contests.

Voters from the Sacramento suburbs ousted the veteran lawmaker in the race for the state's newly redrawn 7th Congressional District. This was the second attempt for Bera, a 45-year-old physician who failed to unseat Lungren two years ago.

Bera defeated Lungren 51.1 percent to 48.9 percent.

His win adds to Democratic gains in California's congressional races. The state's majority party benefited from an independent redistricting process that was in full effect for the first time this year.

Before the Nov. 6 election, California's congressional delegation had 33 Democrats, 19 Republicans and one vacancy in a Democratic district. With one congressional race yet to be called, the 52nd district in San Diego, the delegation had shifted to 37 Democrats and 15 Republicans.

Lungren, 66, is a former state attorney general who served nine terms in Congress. He reported raising more than $2.2 million for his campaign through the third quarter's close, while Bera reported raising more than $2.7 million through the same period.

It was one of the California congressional races that drew intense interest nationally, after gerrymandered strongholds were transformed into free-for-alls because of the independent redistricting process. Their contest was one of the most expensive congressional races in the country, with outside groups pouring in more than $8.3 million.

Neither candidate could be reached immediately for comment Thursday night.

Lungren's loss comes amid a Democratic landslide in California during the general election. Democrats picked up other seats in the nation's largest congressional delegation and grabbed supermajorities in both houses of the Legislature.

The GOP has been hit by twin forces in California -- a declining number of voters registered as Republican and the independent redistricting, which meant some GOP incumbents faced vastly different constituencies than when they were first elected.

Longtime Republican Rep. Mary Bono Mack lost her seat to Democrat Raul Ruiz, a Harvard-educated physician who mobilized the district's growing swath of Hispanic voters. In San Diego, incumbent Republican Rep. Brian Bilbray was losing ground to Democratic challenger Scott Peters.

The heavier Democratic tilt in California has national implications because it helps position the party for 2014, when it hopes to reclaim the majority in the House of Representatives.

County registrars have 28 days after the election to finalize results under California law, but any candidate or voter can ask for a recount within the following five days. It was not immediately clear whether Lungren would ask for one.