Republican Carl DeMaio is holding on to a very slight lead in the extremely tight race for California's 52nd Congressional District in San Diego. He is ahead of one-term U.S. Rep. Scott Peters (D) by less than one percentage point.

One hundred percent of precincts have reported in, but according to the county registrar, approximately 180,000 mail and provisional ballots have not been counted.

The amount spent by outside groups has totaled in the millions as both national parties flooded the San Diego district with mailers and television ads. Despite both parties' antics, however, independents will be the key voting demographic in determining the outcome of the race.

Earlier polling conducted in September by SurveyUSA reported Peters ahead of DeMaio by one percent among likely votes heading into Election Day. While each candidate maintained over 40 percent of likely independent voters, DeMaio was able to edge out the win.

The district's registered voter population consists of about 390,000 voters -- 29 percent of whom are not affiliated with either major party. According to the secretary of state, Republican registration continues to edge Democratic registration at

34 percent to the Democrats' 32 percent.

Peters took first place during June's nonpartisan, top-two open primary election with 42.3 percent of the vote. DeMaio took the runner up spot with 35.3 percent of the vote.

In previous interviews with IVN, both candidates made their appeal to independent voters.

Peters highlighted his fiscally responsible record by pointing to his sponsored legislation on health care and the economy.

“[San Diegans] just want people to be able to work together to get things to happen. That’s been my history and I think I’ve shown it again in Congress and that’s what people are noticing,” he said.

DeMaio emphasized his willingness to buck the party line on social issues like gay marriage and abortion.

“This is a seat that reflects the future of America and that is that we are fiscally responsible and socially accepting,” DeMaio said. “I think I’m a candidate that fits this district.”

Both candidates traded barbs at an October forum at La Jolla Country Day School. The last months of the election were mostly defined by back-and-forth partisan attacks and negative ads from both campaigns.

Editor's note: The initial published draft of this article said Republican Carl DeMaio won the election. While 100 percent of precincts have reported in, there are still tens of thousands of mail and provisional ballots that still need to be counted. The article has been updated to reflect this information.

Photo Source: KPBS