Two conservative candidates face off in Utah's Republican Senate primary tonight, and the winner will likely become the state's next U.S. senator. Both want to curtail spending; both want to limit government; both want to repeal health care reform. Both have the backing of Tea Partiers in their state.

But only one has the endorsement of nationally prominent Tea-Party-related groups, so when attorney Mike Lee and businessman Tim Bridgewater face off in tonight's primary, it could be a test for the Tea Party establishment, counterintuitive as that term is.

If there's such a thing as the Tea Party movement's establishment, it consists of a handful of influential groups that have shown a willingness to back the candidates that Tea Partiers support: the free-enterprise Club for Growth, the Dick-Armey-led FreedomWorks, and, as of more recently, Tea Party Express.

Lee has drawn the backing of both FreedomWorks and Tea Party Express. The groups haven't spent too much money on his behalf--as of last Thursday, Tea Party Express had spent $22,000 and FreedomWorks' PAC had spent under $3,000--but Tea Party Express has been sending emails to supporters asking for money and support for Lee.

Together, Lee and Bridgewater defeated incumbent Republican Sen. Bob Bennett at the state GOP convention in May, knocking him off the ballot of his own reelection race in the second round of voting by thousands of delegates chosen in statewide caucuses earlier this year. They both symbolize a new wave of conservatism that has cost Bennett (who wasn't particularly liberal, himself) his Senate seat.

The race is a close one. Bridgewater outperformed Lee at the state convention, despite expectations, taking 57% of delegate votes to Lee's 43% in the final round of voting. (Had he reached 60%, Bridgewater would have sealed the nomination then and there.)

It is likely that neither Tea Party Express nor FreedomWorks will be too upset if Lee loses. The Club for Growth, for its part, met with multiple candidates and chose to endorse neither Lee nor Bridgewater, content that more than one player in the multi-way primary stood close enough to the Club on its free-market agenda. It instead ran ads attacking Bennett, seeking only to bring him down.

Both Lee and Bridgewater enjoy backing from Tea Partiers in the state of Utah; David Kirkham, an early and prominent leader in the Tea Party movement in Utah endorsed Bridgewater on Monday, saying that claims of a Tea-Party-writ-large endorsement of Lee "a little presumptuous and premature." (For the record, I'm not sure either group has made such claims.)

It's questionable how much the Tea Party Express and FreedomWorks endorsements mean for Lee, anyway. "I do not think that the endorsements, at this point in time, are gonna make any difference," Utah GOP Chairman Dave Hansen said. As far as Utah Tea Partiers go, Hansen says their support appears to be split between Lee and Bridgewater.

The Washington Post called tonight's primary a test for the Tea Party, and for its ability to pick out a single candidate and propel him or her to victory. While that's true, it's worth narrowing a bit: it's a test for the most prominent groups in the Tea Party, not just for the movement as a whole--and mostly for the brand equity of their endorsements.

Since neither group has spent too much on the primary, the value of their endorsements, largely, rests in the Tea-Party brand identity Tea Party Express supplies, the credibility FreedomWorks has on the right, and the e-mails Tea Party Express sends out to its supporters, encouraging them to contribute to Lee and (for those in Utah) to vote for him. A Tea-Party-friendly candidate will emerge regardless; these groups, shrewdly, have held off pouring hundreds of thousands of dollars into the primary race as a result.

Tonight, we'll find out how far an endorsement from prominent, national Tea Party groups can take a candidate in a race against another Tea Party candidate.

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