(CNN) - Florida's closely watched junior senator said Tuesday his state's primary election would determine the eventual GOP nominee.
Speaking on CNN's "Starting Point with Soledad O'Brien," Republican Marco Rubio said he wouldn't handicap the race, but could predict the importance of winning the Sunshine State.
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"I'm not going to speculate as to who's going to win," Rubio said. "Here's what I'm comfortable saying. I think the winner of Florida is in all likelihood going to be the nominee of our party. Florida is a mini America. Virtually every issue we want them to be conversant on is a discussion we've had in Florida."
Rubio, who hasn't endorsed a GOP presidential candidate ahead of Tuesday's primary, said his standing relationships with Mitt Romney and Newt Gingrich prevented him from publicly backing one over the other. Rubio said Gingrich helped him during his time in Florida's state legislature, and Romney campaigned on his behalf in his 2010 Senate bid.
"I have relationships with two of the four candidates," Rubio said. "I know them well. I didn't want to get involved in the endorsement game. None of it will matter at the end of the day. My endorsement won't impact the outcome at the end of the day. Voters will make up their own minds, and we are going to find out tonight what Floridians think."
The onslaught of negative ads in Florida has previewed what's in store during the general election, Rubio said.
"I think that's been a part of every campaign," Rubio said. "Unfortunately, it's only gotten worse. No candidate in American history has ever run more negative ads than Barack Obama. I don't think that will change in 2012. Unfortunately people have to get used to it. I think voters see through that."
Though political observers have pegged Rubio as a strong potential vice presidential pick, the Florida senator reiterated Tuesday what he's said in the past: he isn't interested in being a running mate, and is focused on his work in Congress.
"I'm not thinking about the vice presidency or anything of that nature," Rubio said.