The Senate Conservatives Fund has endorsed retired Air Force Col. Rob Maness over Rep. Bill Cassidy in Louisiana’s GOP primary for Senate, throwing its support behind a conservative underdog in one of the cycle’s most competitive races.

“Colonel Rob Maness … understands the value of our freedoms and will fight to repeal Obamacare and stop the massive spending, bailouts, and debt that are bankrupting our country,” said Matt Hoskins, the executive director of Senate Conservatives Fund, in a Monday news release. “He offers voters a compelling choice over Senator Mary Landrieu because he’s not a Washington insider.”

Cassidy and Maness are looking to unseat three-term Democratic Sen. Mary Landrieu, a top target for Republicans in 2014. Some local Republicans have criticized Cassidy’s conservative credentials, meanwhile a couple local lawmakers are considering jumping into the GOP primary as well.

Landrieu has won three Senate terms in a state that GOP presidential candidates have carried in every presidential cycle since 2000.

The Louisiana Senate race is rated a Tossup by Rothenberg Political Report/Roll Call.