MIAMI — When Florida Gov. Ron DeSantis picked Ashley Moody for his state’s Senate seat Thursday, he turned to a rising star in state politics, a harsh critic of President Joe Biden and one of his closest political allies to send to Washington.

Moody, when she replaces the State Department-bound Marco Rubio, will add a notably younger voice to the Senate. Moody, 49, will be one of just a dozen senators under the age of 50 when she takes office and will become Florida’s second-ever female senator. As state attorney general, she has made her name by repeatedly suing the Biden administration, including on illegal immigration, transgender rights, Covid-19 policies and student loan forgiveness.

Moody will take office just in time for President-elect Donald Trump’s return to Washington. She was the only Florida Cabinet-level official who endorsed DeSantis over Trump during the 2024 primaries, which could be seen as a demerit for a president famous for keeping score and holding grudges — but since DeSantis ended his bid, she has steadfastly portrayed herself as a MAGA loyalist.

“I can get a binder on somebody, I can watch some of their interviews, whatever. But I’ve also been alive working for six years alongside the attorney general. And she’s never let us down once — not one time in six years,” DeSantis said during a news conference in Orlando announcing Moody’s pick. “She was always someone that was near the top of the list.”

Throughout the selection process — and during his announcement on Thursday — DeSantis stressed that his pick would do whatever possible to help enact Trump’s agenda, something Moody herself repeatedly affirmed in her short speech accepting the role. The onetime presidential primary rivals have worked to repair their relationship, and met for an outing of golf on Tuesday.

The Senate seat became available after Trump picked Rubio — another onetime opponent turned ally — to serve as secretary of State in his incoming administration. Moody has very little time to settle into her new job before she must fight to keep it: The seat will open up again for a special election in 2026 and the victor will serve for two years before the seat again comes up for a regularly scheduled election in 2028. DeSantis previously told reporters that having someone to “potentially be up there a long time” was a key factor in his decision.

Should Moody run in two years — as most anticipate she will — she likely will face a competitive Republican primary. Rep. Cory Mills (R-Fla.), who DeSantis acknowledged on Thursday he considered for the appointment, said before Moody was selected “you can probably guarantee” he will run in 2026. And he said Thursday that hasn’t changed.

“We’re still considering the seat in ‘26,” Mills said in an interview after Moody was announced. Mills also noted he texted Trump to get his thoughts following the Moody announcement.

The Trump transition did not immediately respond to a request for comment about DeSantis’ selection. But Trump has publicly praised the Florida-run investigation into the apparent assassination attempt at his golf course in the state last year, which Moody has been the public face of.

The Senate decision gave DeSantis, who is term-limited out in early 2027, a powerful opportunity to shape his legacy and reshuffle the deck of Florida leadership. He officially offered Moody the job on Wednesday night, he said.

DeSantis signaled for weeks that Moody was a lead contender even as he publicly said he was undecided about the position. In December, Moody filed state attempted felony murder charges against Trump’s alleged would-be assassin Ryan Routh, alleging that serious injuries of a six-year-old girl were caused during a related traffic accident. In delivering the news, Moody echoed Trump’s claim that the federal investigation into the assassination attempt couldn’t be trusted.

This month, Moody appeared at a local swearing-in ceremony in Hillsborough County with Pam Bondi, a trusted Trump ally who’s on her way to be the next attorney general. Moody led a letter of state attorneys general to encourage the Senate to confirm Bondi and signed onto a pledge with other GOP state attorneys general to support Trump’s policies on illegal immigration. DeSantis praised Moody as someone who “never had any blemish on immigration.”

“It was always strong, he said. “She’s never been a squish on any of these issues … She’ll go up there and she’ll be part of the enforcement caucus.”

Sen. Katie Britt (R-Ala.) gushed about Moody’s “brilliant intellect” during a Senate Judiciary hearing aimed at confirming Bondi on Thursday, saying she was “thrilled” to have another woman in the upper chamber.

The elevation of Moody to the Senate marks a long evolution in her politics. Moody was once a college Democrat whose family sued Trump, alleging fraud over a condominium that was never built. Her father was a federal judge appointed to the Middle District of Florida in 2000 by then-President Bill Clinton.

She was president of the student leadership group Florida Blue Key when she attended college at the University of Florida. At 31, she was elected as a circuit judge in Hillsborough County. Though she won her Florida attorney general race in 2018, the fact that she was a registered Democrat until 1998 — the year Jeb Bush was elected governor — was used against her in the GOP primary.

She has become a fierce defender of DeSantis and his agenda, while also repeatedly tangling with the Biden administration. By mid-2024 Moody and her office had been involved in more than 40 cases against the federal government, some of them as the lead plaintiff or in support of litigation filed by other states.

In 2020, she signed onto a brief filed by several Republican-led states that asked the Supreme Court to consider a last-minute challenge to throw out millions of votes cast in battleground states that Trump lost. Moody last year tried to convince the state Supreme Court to block amendments dealing with recreational marijuana and abortion access from the November ballot in Florida, but the court ultimately ruled against her.

Republican Party of Florida chair Evan Power called Moody an “excellent pick” who’ll be a “critical voice” in the Senate.

“Florida Attorney General Ashley Moody has a proven track record on the issues that matter most to Floridians, border security being one of them,” he said.

Moody was one of several candidates who was vetted by DeSantis. Aside from Mills, the governor said he also talked to Rep. Kat Cammack (R-Fla.) about the position.

Moody’s path for selection became clearer once Lara Trump, Trump’s daughter-in-law and former co-chair of the Republican National Committee, took herself out of the running for the seat. DeSantis hadn’t given any indication that he might choose her, or whether the two had spoken, but he faced online pressure from MAGA-aligned forces to install her in the seat.

Moody had also been considering the 2026 governor’s race. That’s expected to yield a competitive GOP primary with possible contenders including former Rep. Matt Gaetz, Rep. Byron Donalds and Agriculture Commissioner Wilton Simpson, all of whom have a closer relationship to Trump than to DeSantis.

Kimberly Leonard reported from Miami, and Gary Fineout reported from Tallahassee, Florida. Mia McCarthy contributed to this report from Washington.