By Lauren Shepherd -- The Hill

 A coalition of centrist Republicans will concentrate its resources on a few key congressional primary races to give voters more like-minded GOP candidates this fall.

Two of them are Mary Ose in California’s 3rd Congressional District race and Sen. Arlen Specter in Pennsylvania.

The coalition, known as the Republican Main Street Partnership, aims to unify Republicans and beat back conservative forces that it says could jeopardize Republican prospects in November.

With only a few days left before California votes Tuesday, Ose remains a close second place in the polls, trailing state Sen. Rico Oller but running ahead of former state Attorney General Dan Lungren.

“That’s a nasty three-way race at this point,” said Rep. Tom Davis (R-Va.) at a Main Street Partnership briefing yesterday. “Oller’s been ahead in everything, but [Ose] is steadily moving up to the point now where I think she’s clearly second and closing.”

“You don’t want to do a [Howard] Dean where you peak three weeks before the primary,” he said.

In January, the Main Street Partnership endorsed Ose, a Sacramento businesswoman who is the sister of Rep. Doug Ose (R). The congressman is not seeking re-election.

Ose has contributed close to $800,000 of her own funds to the race. The Main Street Partnership has contributed $5,000 to her campaign.

Sarah Chamberlain Resnick, the group’s executive director, said the group has about $1 million to spend on congressional races this year and the money will be split evenly between primaries and the general election.

She and Davis both said the group would spend substantially more money in this year’s races than in previous years. They are hopeful that the money will have particular impact on this year’s primary campaigns.

“I think we’re going spend more money than usual, period, and probably more time than usual, period,” Davis said.

He said group members are eager to be “impact players” in several primary races to give the party the best chance in the general election by nominating moderate candidates.

“It’s driven by the fact that you have other groups that are playing in primaries that we just can’t leave the field exclusively to them,” he said.

One such organization, a Washington-based conservative interest group called Club for Growth, has endorsed candidates in several races targeted by Davis’s group.

In Pennsylvania, for example, Club for Growth endorsed Rep. Pat Toomey, a fiscal and social conservative running for the Senate against Specter, who is widely regarded as one of the most centrist of Republicans.

Davis said a Republican primary typically draws more conservative voters to the polls, which could help Toomey’s prospects. But in a general election with higher turnout, he said, Specter is the only person who can win.

“He gets a huge crossover vote,” Davis said.

Also in Pennsylvania, the Main Street Partnership is supporting Melissa Brown, who is locked in a close primary race with Chamber of Commerce President Al Taubenberger and state Rep. Ellen M. Bard for the 13th Congressional District seat.

At the briefing, Davis said the group is also endorsing four other House candidates, including incumbent Rep. Sherwood Boehlert in New York’s 24th District and naval officer and pilot Adam Taff in the Kansas 3rd District race. It is also supporting two other Senate candidates: Reps. George Nethercutt (Wash.) and Johnny Isakson (Ga.).

Davis said the coalition might also become involved in several other congressional races, including the Republican primary in Louisiana’s 1st District and the 17th District race in Texas.

For its part, the Club for Growth has targeted several of those races, including the one in Texas. Although the group says it backs candidates based on their fiscal records, Davis said it endorses candidates who are much more socially conservative than the mainstream.

“The more stringent they are on social issues, the more likely they are to come in,” he said, adding that when the group becomes involved in the race his “antenna goes up and says, Is there anybody better?”

But David Keating, executive director of the Club for Growth, called Davis’s comments “ridiculous.”

“It should set a warning flag if we haven’t endorsed the other person,” Keating said.

Keating said his group only looks at a candidate’s fiscal record without applying a litmus test on social issues, such as gay marriage and abortion.

“I’m sure in the general election, we’ll wind up agreeing on a lot of candidates,” he added.

Davis said regardless of who is chosen in the primaries, Republicans should remain cautious about being too optimistic in the general election.

“Voters don’t really trust either party,” he cautioned, saying voters are hesitant to allow one party to be in control of both the White House and both houses of Congress.

He pointed to the 1992 election, when voters swept Democrats into a majority in both Houses and elected Bill Clinton to the presidency. But in 1994, the voters decided to give the Republicans a chance.

“Voters make the corrections,” he said. “There is a group of people there that get uncomfortable when one party takes everything.”