Sen. Rand Paul is backing state Sen. Kelli Ward in the GOP primary in the newly open Arizona Senate race. The Kentucky Republican is the first sitting senator to back Ward’s campaign.

Ward was originally challenging GOP Sen. Jeff Flake, who has been sharply critical of President Donald Trump. But with Flake recently announcing his retirement, the field is now open for other GOP hopefuls to run for Senate. Ward has also received support from former Trump adviser Steve Bannon, who has said he wants to take on every GOP Senate incumbent except Sen. Ted Cruz, R-Texas.

“Honored to have the support of Senator @RandPaul — AZ needs a US Senator who values #liberty, freedom, & the #Constitution #NewGOP” Ward’s campaign account tweeted Wednesday.

Paul cited their similar experiences as doctors — Ward in family medicine and Paul as an eye doctor — in his statement endorsing Ward.

“As a fellow physician, Dr. Ward witnessed firsthand the damage Obamacare has inflicted on our nation’s healthcare system,” said Paul. “As senator, she will bring a new voice and a fresh perspective to the Senate.”