President Donald Trump‘s former chief physician, Dr. Ronny Jackson, won a House GOP primary in Texas on Tuesday, and will go on to fight to replace 13th District Rep. Mac Thornberry (R), who had announced last year he would not seek reelection.

Jackson had secured Trump’s endorsement, while Thornberry had thrown his support behind the other GOP challenger, cattle industry lobbyist Josh Winegarner.

Jackson edged out Winegarner with 55.6% of the vote, compared to Winegarner’s 44.4%.

The district is expected to stay in the hands of the GOP, as it is solidly conservative and was carried by Trump by more than 60 points in 2016.

Trump celebrated Jackson’s win on Twitter, tweeting on Tuesday that he “will be a fantastic Congressman.”

“Congratulations to @RonnyJackson4TX on a big win against a tough and really good opponent. Ronny will be a fantastic Congressman,” Trump wrote. “Will represent the wonderful people of the Great State of Texas, and the USA, very well. Proud of you Ronny!!!”

 

Jackson tweeted separately that he had spoken to the president over the phone after his win and is “honored to be the Republican nominee for #TX13.”

Other prominent Republican figures, including Donald Trump Jr., Eric Trump and Sen. Lindsey Graham, joined in on Twitter congratulating him as well.

“Ronny is a strong conservative who will accomplish great things for our military and our country in Congress!” Graham wrote.

Jackson, a retired rear admiral, retired from the Navy last December and previously served as the White House physician during the Obama administration as well.

In his run, Jackson promoted the rightwing conspiracy that former President Barack Obama had spied on the Trump campaign, upsetting several of his former colleagues.

He had also been under consideration for Secretary of Veteran Affairs, but withdrew over allegations that he was “abusive” toward coworkers, lax with prescription pain medications and occasionally intoxicated. He has vehemently denied all accusations as “completely false and fabricated.”

Jackson gained the national spotlight when he praised Trump’s body in a White House briefing, leading him to be mocked on Saturday Night Live.