Sen. John Cornyn, the second-highest ranking Republican in the Senate, drew a last-minute primary challenger today when Rep. Steve Stockman, R-Texas, filed paperwork for the 2014 Texas Senate race, just minutes before the filing deadline.

"Stockman withdrew his application for his current seat and filed to run in the U.S. Senate race," Spencer Yeldell, a spokesman for the Republican Party of Texas, confirmed to ABC News.

The announcement came as a surprise for those who thought Cornyn would run without a serious opponent, but the match-up echoes the trend seen in many Senate races across the country next year with a tea party candidate challenging the establishment-backed incumbents.

On Friday, Sen. Thad Cochran, R-Miss., announced he would seek re-election for a seventh term, setting up one of the biggest establishment vs. tea party races in 2014.

Cornyn, who is seeking his third term, may be forced to move further right on issues with a challenger like Stockman, a first-term congressman who has been vocal in his criticism of the administration.

The National Republican Senatorial Committee plans to back Cornyn's bid.

"We are proud to support Sen. Cornyn and while this primary challenge is quite the head scratcher, it will be defeated," Brad Dayspring, communications director for the NRSC, tweeted today.

It is unknown whether conservative groups like the Senate Conservatives Fund and Club for Growth, who are backing many candidates challenging incumbents, will support Stockman.

The Senate primary in Texas will be on March 4.