Family Research Council President Tony Perkins is endorsing Rep. Bill Cassidy (R-La.) in his runoff against Sen. Mary LandrieuMary Loretta LandrieuLandrieu dynasty faces a pause in Louisiana Senate GOP rejects Trump’s call to go big on gun legislation Project Veritas at risk of losing fundraising license in New York, AG warns MORE, reversing course to show unity within the GOP.

Perkins initially endorsed Tea Party-backed Col. Rob Maness in part because of concerns with Cassidy’s conservative values. Cassidy, along with a handful of Republicans, joined Democrats in 2009 to pass a law that made assaulting a person based on their sexual orientation a crime.

But Perkins changed his mind Thursday based on a conversation with Cassidy and after hearing him bash laws that could “use legal intimidation to attempt to limit freedom of faith and freedom of speech.”

“Because I believe you to be a man of principle and a man of your word, I am encouraged by these latest developments,” he wrote in a letter to Cassidy provided to The Hill. 

“It is critical to the pro-family movement in America that any conservative elected to the U.S. Senate clearly understands and acknowledges the severity of the threats posed to religious liberty—our first freedom—and pledges to defend it.”

On Election Night, Perkins told The Hill that he didn’t see himself supporting Cassidy without serious “assurances,” which he received in the subsequent days. 

“We support conservatives that are going to advance the core values that we advocate for and he has not convinced me,” Perkins said on Election Day. “Someone that has a track record of working against those core value is not someone that I’m interested in supporting.”

Perkins also added that he thought Cassidy would have a “hard time” winning unless control of the Senate hung in the balance. The GOP’s command over the body isn’t in jeopardy, but the Democratic Senatorial Campaign Committee has cancelled a portion of their ad buys for the runoff.

Maness is also joining Cassidy in a show of unity, his campaign said. Both men and their wives went on a double date Friday night in New Orleans and Maness will join Cassidy and Sen. Rand PaulRandal (Rand) Howard PaulGOP senators introduce Trump's plan to claw back billion in spending Pro-Trump super PAC raises .5 million in 6 weeks Trump has exposed Democratic hypocrisy on prison reform MORE (R-Ky.) for a campaign event on Monday in Baton Rouge.