First Nevada, then Arizona, and now Utah: the Tea Party Express bus tour is rolling through three states with contentious Senate races in its opening salvo of tour dates.

In doing so, it's offering conservative challengers a chance to attend rallies and court support from tea partiers as they try to gain steam against incumbent senators.

On Saturday, Sarah Palin kicked off the bus tour at a rally in Searchlight, Nevada, hometown of embattled Senate Majority Leader Harry Reid. The tour also stopped in Laughlin and Las Vegas.

It's unclear which Republican will slog through the primary and become Reid's challenger, but he trails both real estate owner Danny Tarkanian and former Nevada GOP Chairwoman Sue Lowden by more than 10 percentage points, on average. A purported tea party candidate, Scott Ashjian--whom some tea partiers have rejected as a fake, although he's running on a Tea Party ticket--could draw some votes away from a Republican candidate and help Reid...except he's facing felony charges, which could complicate things.

Tarkanian and Lowden, along with fellow Reid challenger and former GOP state lawmaker Sharron Angle, were on hand for the Searchlight rally, courting support from the tea party crowd.

Then it was on to Arizona, where Sen. John McCain is facing a tough primary challenge from conservative radio host J.D. Hayworth.

The Tea Party Express stopped for rallies in Flagstaff and Phoenix on Sunday; Hayworth attended both. Luckily for McCain, Palin had spent Friday and Saturday morning campaigning for him in the state.

Now the bus tour is rolling on through Utah, where Republican Sen. Bob Bennett, a three-term incumbent, may lose his reelection primary to a conservative challenger.

Tea Party Express stopped for a rally in St. George on Monday afternoon, and it will hold two more events in Provo and Salt Lake City on Tuesday.

Bennett faces no less than seven challengers, and a strong anti-Bennett contingent turned out for the GOP caucuses last week. Caucus-goers elected delegates to the Utah GOP's May 8 nominating convention, and if 60% of those delegates coalesce around a challenger to Bennett, the senator could lose his spot on the ballot as a Republican in November. At this point, that looks like a possibility.

Two of the leading challengers, attorney Mike Lee and businessman Tim Bridgewater, are attending all three events, their campaigns confirmed.

Next up for the Tea Party Express: Colorado, where Democratic Sen. Michael Bennet (brother of Atlantic editor James Bennet) is facing a tough primary challenge from former Colorado House Speaker Andrew Romanoff and polls neck-and-neck with two Republicans, former Lt. Gov. Jane Norton and district attorney Ken Buck.

The tour will stop in Grand Junction and Denver on Wednesday, before moving on to Nebraska, Kansas, Oklahoma, Arkansas, and Mississippi later this week.

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