Just six short months ago, Marco Rubio had his eyes set on a seat in the Oval Office. Now, the ambitious leader hopes to continue making positive political changes as Florida’s incumbent senator in what will surely be one of the most heated senatorial elections of the year.  Rubio is battling it out with Democrat Patrick Murphy for a seat in one of nine battleground states this year.

While Rubio was in the presidential race it seemed to many that he would not seek to retain his seat in the senate. Republicans were preparing for a battle between the likes of David Jolly, Carlos Beruff, Ron DeSantis and Carlos López-Cantera. However, upon announcing his intent to retain his seat, Rubio wound up surging back, dominating the election, receiving about 72% of the vote.

Democrat Patrick Murphy found similar success in his party’s primary, receiving about 59 percent of the vote to top Alan Grayson and Pam Keith.

The battle for the senate seat between Murphy and Rubio will be a big player in determining what party controls the upper chamber. Thus far, the battle has taken a predictably combative turn.

Murphy has been investigated by the FEC for allegations that he accepted illegal campaign donations during his run in 2011. Despite the alleged misconduct occurring five years ago, the FEC has begun investigating recently, though the Murphy campaign has claimed the candidate will be cleared of wrongdoing.

Rubio, however, hasn’t pulled many punches when it has come to criticizing his opponent, calling him “hyper-partisan,” and insinuating Murphy’s credentials are lackluster or, in some cases, fabricated. Murphy hasn’t been hesitant to strike back, indicating that the battle for Florida’s senate seat will be both competitive and worth paying attention to as both parties battle for control.

According to RealClearPolitics, the race for the senate seat is a tight one, with recent polling indicating Rubio ahead by about 3 points. Despite this, Cook Political has named the Florida race as a “toss-up,” indicating a very real possibility that the election could go either way come November 8.