AP Photo/John Raoux
Sen. Marco Rubio.
The seat, which will be crucial in the battle over control of the Senate, looks to be leaning in favor of the one-time 2016 presidential hopeful.
In the RealClearPolitics polling average, Rubio holds a 3.7-point lead over Murphy.
Data-journalism outlet FiveThirtyEight gives Rubio a nearly 90% chance of winning the seat Tuesday.
Rubio made a failed bid for the presidency in 2016, falling well short of the nomination even though many pundits concluded early in the race that he was the favorite to win. He earlier announced he would not seek reelection to the Senate, a body he was not much of a fan of. But, he made a late June entry into the Republican primary race for his seat after a deadly nightclub shooting in Orlando.
Murphy, just 33-years-old and seeking to become the youngest member of the Senate, was a Republican himself until 2011. His business career faced intense scrutiny in the 2016 race, with reports showing Murphy had exaggerated his credentials. Still, he received plenty of help along the trail from big-name Democrats such as President Barack Obama, Vice President Joe Biden, and Democratic nominee Hillary Clinton, who all sought to cost Rubio his Senate seat.
Florida polls close at 8 p.m. EST.