“No matter who’s elected president, there’s reason to worry,” Rubio said. “If it’s Hillary Clinton, you know we’re going to have four more years of the same failed economic policies, four more years of the same failed foreign policy. The prospect of a Trump presidency is also worriesome to me in many ways. It’s no secret that I have significant disagreements with Donald.”

He continued, “I think that the point that really drove me to change my mind is that as we enter this kind of new chapter in our history here is, there’s another role the Senate plays that I think can be really important in the years to come. And that’s the power given to it in the Constitution to act as a check and balance on the excess of the president. It’s even more important given the fact that control of the Senate could very well come down to what happens in the Florida race.”

Rubio also declined to say whether he would campaign with Trump in the state, citing his focus on his own Senate contest.

“We’re going to be focused on our own campaign and the things we stand for, and that’s what we’re going to stand on in this campaign,” Rubio told C-SPAN. “So at this point, my intention is to campaign on me and what I stand for, and we have some significant policy differences with Donald — and obviously, I have entirely different policy of Hillary Clinton. So we’re going to focus on the Senate, we’re going to focus on my race for the Senate and the role the Senate needs to play in this republic for the next six years.”

In a Quinnipiac University poll released Wednesday Rubio led Rep. Patrick Murphy, a Democrat, 47 percent to 40 percent.

The move is only the latest in a roller coaster ride for the one-time Tea Party favorite, who campaigned for nearly a calendar year for the GOP nomination, only to lose his home state in embarrassing fashion to Trump in Florida. Rubio won only one of the state’s 67 counties (Miami-Dade) before suspending his bid, sparking a three-month guessing game regarding his political future prior to his decision.

The former presidential candidate first indicated a possible change of heart last week after reports that Lt. Gov. Carlos Lopez-Cantera, a longtime friend of Rubio, had pressed him to reconsider his future and entertain a possible re-election bid in the wake of the Orlando shooting. He responded soon after, saying he would re-evaluate his options with his family. Lopez-Cantera officially dropped his bid shortly after Rubio announced he was in.

The majority of the Republican field for his seat intimated ahead of time that they would vacate the race if Rubio were to seak re-election, including Rep. Ron DeSantis and Lopez-Cantera. Rep. David Jolly announced late last week that he would seek re-election to the House in the 13th Congressional district against former Gov. Charlie Crist.

However, businessman Carlos Beruff has indicated he will remain in the primary contest and will spend upwards of $15 million on his bid for the GOP nod against Rubio. He has already dumped $4 million into the campaign thus far.

Prior to his entry, no one within the GOP primary field had been able to gain traction, especially against Murphy, who had been leading most polls and is the likely Democratic nominee for the seat. Over the weekend, Murphy teased a possible race against Rubio, calling him the “most homophobic senator” in the country. Murphy is trying to fend of far-left Rep. Alan Grayson, who has drawn the ire of many within his own party, including Senate Minority Leader Harry Reid.

The National Review first reported Wednesday morning that Rubio “has begun telling colleagues he will run for re-election to the Senate.”

The second campaign in a year comes on the heels of his White House bid, which was marred by two instances: a poor debate performance prior to the New Hampshire primary which halted his momentum and his attacks on Trump, during which he questioned the size of his genetalia prior to Super Tuesday.

Two weeks later, his campaign was over.

Long viewed as a rising star within the party, Rubio’s decision comes after constant prodding from GOP leadership, with Senate Majority Leader Mitch McConnell leading the effort for him to reconsider. Rubio recently even poked fun at his campaign trail stump speech, tweeting that he had “only said like 10,000 times I will be a private citizen in January.”

Despite dropping out following his March 15 drubbing in Florida, the incumbent senator finished third in the delegate count after winning only three contests (Minnesota, the District of Columbia, and Puerto Rico) even though Ohio Gov. John Kasich was the final Republican to suspend their bid for the White House following the Indiana primary.

However, he’s incurred a stream of criticism from some within the GOP for his decision to vote for Donald Trump in the general election despite standing by his constant stream of attacks against the presumptive nominee. During the latter stages of the race, Rubio called Trump a “con artist” and “dangerous,” adding that he is unqualified to have access to the nation’s nuclear codes.

The run, however, poses risks for the Florida Republican — namely, the possibility of him dropping a second statewide contest in a eight month’s time. A second loss could be a crippling blow to his political future and any hopes of running for president again, which he has openly talked about since exiting the presidential contest in March. However, much of the party (including Trump) pushed for his entry in the race and plans to back him.

Ultimately though, Rubio could be on the receiving end of two major political defeats, which could spell the end of his future in major party politics and come largely at the hands of Trump.

Ironically, the same hands he poked fun at could help send him into political exile.

Senior Congressional Correspondent David M. Drucker contributed to the report.