Republican Rep. Dan Lungren's return to Congress remained in jeopardy Tuesday, with the Gold River Republican and Democratic challenger Ami Bera locked in a near dead heat for a suburban Sacramento House seat.

With all precincts reporting, Bera held a slight lead over Lungren, 50.1 percent to 49.9 percent, with only 184 votes separating the 7th Congressional District candidates.

Both candidates praised get-out-the-vote efforts by their paid staff and volunteers.

Lungren credited his campaign with conducting "the single best precinct operation I've ever seen."

"We think we outworked them. We did it in true conservative Republican fashion," he told about 100 supporters gathered at the Zinfandel California Cuisine restaurant in Gold River.

At an election night party in Carmichael, Bera heralded the work of what he called "the largest grass-roots operation in the U.S."

The battle for the 7th Congressional District, one of the country's most competitive House contests, often highlighted the stark personal and political differences between the two candidates.

Unlike some incumbents in the current political environment, Lungren embraced his decades-long career in politics, including two separate stints in Congress, eight years as attorney general and a 1998 run for governor. He played up his conservative bona fides and often touted accomplishments from years ago, including his role in helping create California's Megan's Law sex offender registry.

Bera, who has never served in public office, positioned himself as an outsider dedicated to changing the governing process. As a centerpiece of his campaign, he pledged to try to pass legislation that would block congressional pay if a budget is not passed on time. The Elk Grove Democrat, who makes his income from a portfolio of rental properties, argued that his background as a physician demonstrated his integrity and commitment to serving the best interests of his constituents.

Tuesday's election wasn't the first time the two rivals went head to head.

Lungren defeated Bera, then a first-time candidate, by seven percentage points in 2010, when the two competed for what was then the 3rd Congressional District.

Several factors made this year's contest more competitive. The state's new political maps created a more compact district contained entirely in east Sacramento County, where Democrats gained a slight voter registration edge over Republicans by Election Day.

The presidential election was expected to draw more voters to the polls than cast ballots in 2010, a dynamic that often favors Democrats in California. Outside spending also gave an edge to Bera this time around. Super PACs, political party committees and other groups poured more than $8 million into the race, making it one of the country's most expensive congressional contests for outside spending. That cash, along with several million dollars spent by the two campaigns, filled the Sacramento airwaves and mailboxes with attacks on hot-button issues such as Medicare, taxes and abortion.

Unlike in 2010, when GOP groups spent heavily to boost Lungren to victory in the final weeks of the campaign, committees backing Bera outspent pro-Lungren forces by several million dollars. The Sierra Club, the Democratic Congressional Campaign Committee and several left-leaning super PACs sought to portray the incumbent as an extreme conservative who sides with Wall Street, big oil and other interests over his constituents in California.

Lungren and his allies, such as the National Republican Congressional Committee, emphasized the economy, hitting Bera on the federal health care overhaul and a past statement suggesting support for increasing the gas tax.

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