A Republican primary for a competitive northern California House race is shaping up to be a showdown between a former House member and the chief aide to one of his top rivals on Capitol Hill.

It’s a GOP battle that shows the schism in the party — and could determine if Democrats keep this sought-after seat in 2014.

Last month, former Rep. Doug Ose and Igor Birman, longtime chief of staff to Ose foe Rep. Tom McClintock, entered the Republican primary for California’s 7th District. They joined autism activist Elizabeth Emken, who announced in June, in a quest to oust freshman Democrat Ami Bera.

Bera represents one of the most competitive districts in the country. In 2012, he defeated Rep. Dan Lungren by just 10,000 votes.

Birman has already made it clear he’s courting the conservative vote, as well as soliciting support from national conservative groups. Local Republicans say Birman is counting on the most conservative candidate winning the nomination.

But if the Republican field ventures to the ideological right in the primary, local strategists warn it could hurt them in the general election. The district is nearly split between Republicans and Democrats, and neither party has an edge among registered voters.

“The 7th District is a strong opportunity for a GOP pickup,” said one longtime California GOP operative. “The district has moderate Democrats and independents in the Sacramento suburbs. But the GOP has primary problems.”

“Igor is right, Ose is center, and Emken is a spoiler,” the operative added.

Privately, GOP operatives say that Ose’s more moderate Republican record is a better fit for the district. President Barack Obama carried it in 2008 and 2012 by at least 4 points.

Ose’s campaign is attuned to the fact that the state’s new open primary system, in which the top two candidates advance to the general regardless of party affiliation, means they’ll have to appeal to both sides of the aisle.

“Right now we are primarily focused on conveying a message about job creation and budget reform to appeal to both Republicans and Democrats,” said Ose spokesman Marko Mlikotin. “One cannot run just a primary strategy, regardless of who the Republican choice is. General election voters are going to be paying attention to the primary, too.”

Birman already has the support of tea-party-affiliated groups such as the FreedomWorks political action committee.

The Club for Growth has also hinted it may get involved in the contest — but GOP observers say the group is waiting for third-quarter fundraising reports to determine what role, if any, it could play. As of press time, none of the candidates had released their third-quarter fundraising reports, which are due to the Federal Election Commission by Oct. 15.

The conservative barrage would be a familiar circumstance for Ose. In 2008, the club helped McClintock defeat Ose in his first comeback bid. They spent heavily to attack his House record. Ose served three terms, from 1999 to 2005.

The attack worked: Ose lost the primary by 15 points.

GOP strategists say a bitter primary battle between Ose and Birman this time around may carve a path to victory for Emken.

She has run two unsuccessful bids for Congress, in 2010 and 2012, and has been willing to use her personal funds for campaigns.

“As Igor and Ose are beating each other up, voters may look for an alternative, and that’s where Elizabeth will pick up the collateral,” said California Republican consultant Jason Roe, an adviser to Emken’s campaign.

No matter who comes through the costly and divisive primary on the GOP side, Democrats argue Bera will be able to sit on the sidelines and stash away his campaign cash for the general.

Republicans counter that California’s early June primary will allow the Republican nominee to rebuild in time to run a competitive race in the general.

“I’m not going to tell you that a contested primary is the optimal situation,” said GOP operative Chris Baker, who is working on Birman’s campaign. “But I also think that it’s not as big of an advantage. … Whoever the nominee is will have several months to refuel and be in a position to financially compete with Bera.”