Texas GOP primary to test tea party's influence.

 Outside groups have spent more than $6.4 million in the Texas GOP primary for the seat of retiring U.S. Sen. Kay Bailey Hutchison, more than any other House or Senate race thus far in the primary season, according to Federal Election Commission filings.

The race pits establishment favorite David Dewhurst, a wealthy self-financing candidate, against the tea party-backed Ted Cruz.

Cruz himself has raised $6.4 million — a fraction of the $21.6 million raised by Dewhurst. Dewhurst’s sum, though, includes more than $15 million that he has contributed or loaned to his own campaign. (Cruz has given his campaign $470,000, according to FEC filings.)

Delayed since March due to redistricting issues, the Texas Republican primary is a chance for the tea party to build on its momentum after its candidate, Richard Mourdock, defeated long-time Sen. Richard Lugar in Indiana’s hotly contested Republican primary in early May.

Anti-tax super PAC Club for Growth Action has spent $2.5 million on ads, mostly opposing Dewhurst, the lieutenant governor of Texas. A pro-Dewhurst super PAC, Texas Conservatives Fund, fought back with $2.3 million in ads against Cruz, Texas’s former solicitor general.

“Moderate, tax-raising David Dewhurst,” is how one Club for Growth Action attack ad described him. This and other ads focused on his support of a state income tax and other “moderate” positions he has taken.

Club for Growth’s single biggest donor, Virginia James, is New Jersey-based investor who has been recognized for her contributions to right-wing organizations, many of which have ties to tea party funders Charles and David Koch.

Another major Club for Growth Action donor is the campaign committee of tea party heavyweight Sen. Jim DeMint (R-S.C.), which has given the group $700,000.

DeMint’s leadership PAC, the Senate Conservatives Fund, itself spent nearly $600,000 on ads supporting Cruz. The leadership PAC has received contributions from the political action committees Koch Industries, AT&T and other major corporations.

Club for Growth's traditional PAC spent more than $41,500.

The pro-Dewhurst Texas Conservatives Fund received a $100,000 contribution from super donor Bob Perry of Texas-based Perry Homes and $100,000 from James Pitcock, Jr., of Williams Brothers Construction, the largest highway construction company in Texas. The super PAC is run by Rob Johnson, former campaign manager for Gov. Rick Perry’s failed GOP presidential bid.

Another pro-Dewhurst super PAC, Conservative Renewal, also received a $100,000 infusion from Pitcock and $500,000 from Texas super donor Harold Simmons.

Former House Majority Leader Dick Armey’s super PAC, FreedomWorks for America, also threw more than $100,000 into the race to support Cruz.

While Dewhurst leads in the polls, they also show he may not carry a full 50 percent, the threshold needed to avoid a runoff in July. If the race goes to a runoff, whoever wins then is expected to take the Senate seat in the general election. A Democratic candidate has not yet been chosen.