Virginia Delegate Robert Marshall says he has the best chance to beat Democrat Tim Kaine in November.
On Monday the Manassas Republican confirmed he will seek the GOP nomination for the U.S. Senate.
Virginia House of Delegates since 1992, Marshall says he has repeatedly challenged Kaine priorities and won.
And he says he has the ability to unite conservatives behind his campaign.
"I'm a person who when I dig my heels in, I get in a fight and I don't measure the odds," Marshall said. " I'm not a go along to get along Republican. I challenge my own leadership, not because I like to get into fights, but because I took an oath to uphold and defend the Constitution." Former Senator George Allen is the frontrunner for the GOP nomination, but the field also includes E. W. Jackson, David McCormick and Jamie Radtke.
Republicans will choose their nominee in a primary June 12.