Marco Rubio, in reversal, will seek re-election to Senate

This moves comes in the wake of a possibility of Republican losing their slight majority in November elections

Former Republican presidential candidate Marco Rubio announced, on Thursday, he will run for re-election to the Senate from Florida, reversing his retirement plans under pressure from GOP leaders determined to hang onto his seat.

"In politics, admitting you've changed your mind is not something most people like to do. But here it goes," Rubio said in a statement. "I have decided to seek re-election to the United States Senate."

The 45-year-old first-term senator had repeatedly described his frustration with the slow-moving Senate, and had been expected to enter the private sector and prepare for another presidential run in 2020.

But he'd been rethinking his plans, particularly following the massacre in Orlando and confronting a pressure campaign led by Senate Majority Leader Mitch McConnell.

With Republicans at risk of losing their slim Senate majority in November's elections, GOP leaders were concerned that the Republican candidates who'd emerged for Rubio's seat were not up to the task of winning in a large, expensive state like Florida amid the political turmoil created by Donald Trump's candidacy.

Trump himself had gotten into the act, tweeting his encouragement to Rubio, whom he dubbed "Little Marco" during the presidential race, to run for re-election.

"Control of the Senate may very well come down to the race in Florida," Rubio said, on Thursday, adding that the outcome also could determine the makeup of the Supreme Court and critical fiscal and economic policies. "The stakes for our nation could not be higher."

Rubio also said that "No matter who is elected president, there is reason for worry." After criticising Democrat Hillary Clinton, Rubio went on to describe his disagreements with Trump, saying that "some of his statements, especially about women and minorities, I find not just offencive 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 proven a willingness to do both." The announcement comes just days ahead of Friday's filing deadline for Rubio's seat.

Republican leaders welcomed the news. "While Marco is already in a strong position to win, Democrats are currently locked in a bruising primary that will produce a weak nominee and cost millions of dollars," said Sen. Roger Wicker of Mississippi, chairman of the National Republican Senatorial Committee.