(CNN) - A national Tea Party group is taking sides in the battle for the Republican Senate nomination in California.
The Tea Party Express will endorse California Assemblyman Chuck DeVore Saturday, a spokesman for the group confirms to CNN. The endorsement is expected to happen at a rally headlined by former Alaska Governor Sarah Palin. The event, in Senate Majority Leader Harry Reid's hometown of Searchlight, Nevada, will kick off the organization's third cross country caravan, which is expected to culminate with a march on Washington by multiple Tea Party groups on tax day, April 15.
Tea Party Express was one of a number of Tea Party groups that helped financially support Republican Scott Brown in his upset victory in January's special senate election in Massachusetts for the seat of the late Democratic Sen. Ted Kennedy.
"We decided to endorse DeVore because we wanted to help with the California primary. We've watched the three Republican campaigns develop and it's clear that Chuck DeVore best represents the Tea Party ideal that we fighting for," Tea Party Express spokesman Levi Russell tells CNN.
News of the endorsement was first reported by the Los Angeles Times.
DeVore is one of three Republicans running to challenge Democratic Sen. Barbara Boxer, who's facing a tough fight in her bid this year for a fourth term in office. Former Hewlett Packard CEO Carly Fiorina, who was an advisor and surrogate to Sen. John McCain's presidential campaign, and former Rep. Tom Campbell, are also battling for the GOP Senate nomination.
A new Public Policy Institute of California poll released Thursday indicates that 24 percent of likely Republican primary voters back Fiorina, with 23 percent supporting Campbell, 8 percent backing DeVore and 44 percent undecided. According to the survey, Boxer is deadlocked with Fiorina and Campbell in hypothetical general election matchups, with Boxer leading DeVore by 6 points in a possible November showdown.
The Public Policy Institute of California poll was conducted March 9-16, with 1,102 likely California voters questioned by telephone. The survey's overall sampling error is plus or minus 3 percentage points.
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