Florida Senator and former Republican presidential contender Marco Rubio announced that he would seek reelection to the US Senate in a written statement publicized Wednesday evening.

Rubio, who prior to Wednesday had insisted he would not run for a second term, explained the about-face.

“In politics, admitting you’ve changed your mind is not something most people like to do,” Rubio wrote. “But here it goes. I have decided to seek reelection to the United States Senate.”

Rubio, who beat expectations in the Iowa caucus in February, was seen as the candidate of choice for the party nomination by many in the GOP establishment before withdrawing from the race after a poor showing in his home state.

When he announced in April 2015 that he would seek his party’s presidential nomination, Rubio said he would not run for reelection to the Senate, even if he failed to secure the GOP nomination.

But the Senator hinted at the possibility of a reelection bid following the Orlando nightclub massacre.

“It really gives you pause,” said Rubio, “to think a little bit about your service to your country and where you can be most useful to your country.”

In justifying his change of heart, Rubio wrote on Wednesday that the US Senate needed strong leadership to rein in executive overreach by the next president.

“[T]here’s another role for the Senate that could end up being its most important in the years to come: The Constitutional power to act as a check and balance on the excesses of a president.”

In his latest criticism of the presumptive GOP nominee, Rubio suggested the Senate would have to remain vigilant – no matter who won in November.

“No matter who is elected president, there is reason for worry.”

Rubio blasted Clinton for advocating “failed economic policies” and a “foreign policy that has allowed radical Islam to spread”.

He also took aim at Trump, however, saying that “The prospect of a Trump presidency is also worrisome to me.”

“His positions on many key issues are still unknown. And some of his statements, especially about women and minorities, I find not just offensive but unacceptable. If he is elected, we will need Senators willing to encourage him in the right direction, and if necessary stand up to him. I’ve a proven willingness to do both.”

If Rubio secures the GOP nod for the Senate race, recent polling shows him well-positioned to defeat either of his likely Democratic challengers.

According to a Quinnipiac poll released on Wednesday, Rubio beat Congressman Patrick Murphy by seven points. The poll also showed Rubio beating Alan Grayson, also a member of the US House of Representatives, by eight points in a hypothetical matchup.