(CNN) - A conservative activist who's challenging a top House Republican Wednesday landed an endorsement from a leading national tea party organization.
But that doesn't seem to be fazing the congressman, Rep. Pete Sessions.
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The Tea Party Express announced it was backing Katrina Pierson in her bid to unseat Sessions, the nine-term congressman from Texas and chairman of the powerful House Rules Committee.
"Katrina has been on the front lines, fighting alongside so many grassroots activists here in Texas, and it's time for us to now stand with her," said a statement from the Tea Party Express.
Sessions appeared to brush off Pierson's primary challenge, telling CNN Wednesday on Capitol Hill that "these things happen."
Asked if he was worried about the challenge, Sessions repeated that "these things happen."
Sessions represents the Lone Star State's 32nd congressional district, a solidly Republican district located around North Dallas.
Pierson will be in the nation's capital on Monday for a meet-and-greet with reporters that's being organized by FreedomWorks, a national conservative grassroots group that endorsed Pierson in September. She also enjoys the backing of conservative firebrand Rafael Cruz, the father of Sen. Ted Cruz of Texas.
But Pierson lags far behind Sessions when it comes to campaign cash. She had $50,000 cash on hand at the end of last year, compared to the nearly $1.3 million Sessions had in the bank.