O’FALLON, Mo. (NewsNation Now) — Eric Greitens, the former Navy SEAL officer who rose quickly to become Missouri’s governor before scandal forced him out of office just a year and a half into his tenure, announced Monday that he will run for the Senate seat being vacated by fellow Republican Roy Blunt.

The announcement by Greitens, 46, came just two weeks after Blunt said he would not seek a third term in 2022. Blunt was first elected in 2011 and is the No. 4 in Senate Republican leadership.

Greitens had been laying the groundwork for a return to politics even before Blunt’s announcement, with increasingly frequent appearances appealing to supporters of former President Donald Trump, who carried Missouri with 57% of the vote in 2020.

A number of other Republican candidates initially showed interest in replacing Blunt in heavily Republican Missouri.

Lt. Gov. Mike Kehoe and Secretary of State Jay Ashcroft have both said they won’t run, leaving Republican Attorney General Eric Schmitt and several of Missouri’s U.S. representatives as potential candidates.

Blunt was the fifth Republican senator to announce he will not seek reelection, a retirement wave that could lead to a heated campaign season next year.

Greitens was a political outsider when he ran for governor in 2016. But beyond his role in the elite military outfit, he was a best-selling author, a Rhodes scholar and had started a successful charity for veterans.

Greitens defeated establishment Republicans in the primary before winning in November. By the end of his first year in office, Greitens was getting buzz as a potential future presidential contender.

It all began to fall apart in January 2018 when a St. Louis TV station aired a report about an extramarital affair with his hairdresser in 2015, before he was elected.

St. Louis Circuit Attorney Kim Gardner, a Democrat, launched an investigation immediately after the media report. The investigation resulted in a grand jury indicting Greitens for invasion of privacy, accusing him of taking a compromising photo of the woman and threatening to use it as blackmail if she ever spoke of the encounter.

Greitens admitted to the affair (he and his wife, Sheena, divorced last year) but denied criminal wrongdoing and accused Gardner of a politically motivated prosecution.

Another scandal followed in April when Gardner charged Greitens with another felony, accusing him of illegally using the donor list for his charity, The Mission Continues, to raise money for his 2016 campaign.

Meanwhile, the Republican-led Missouri Legislature began considering whether to pursue impeachment proceedings. Those discussions and the criminal charges came to an end when Greitens resigned in June 2018.

His return to public life has been gradual. He successfully sought reinstatement to the Navy, though not as a SEAL officer, in 2019. He passed out masks to first responders across the state in the early days of the coronavirus pandemic last spring. He has launched his own television show on the internet and Dish TV and is appearing often on conservative TV and radio programs.

Democrats seeking the Senate seat are Marine veteran Lucas Kunce, former state Sen. Scott Sifton and activist Timothy Shepard.

The other Missouri senator is Republican Sen. Josh Hawley.