NASHVILLE (AP) — Tennessee Gov. Bill Haslam on Thursday endorsed Marco Rubio for the Republican presidential nomination, hoping to give the Florida senator a boost in the state's Super Tuesday primary next week.

Haslam, a popular second-term governor, said he decided to endorse Rubio because he thinks he would have the best chance to beat the Democratic nominee in the general election.

"To win in November, conservatives need a candidate who inspires Americans from all backgrounds," Haslam said. "With Marco standing next to Hillary Clinton on a debate stage, the choice between the future and the past will be clear to every American."

Tennessee is among 11 states holding their Republican presidential primaries on Tuesday, when the biggest single-day haul of delegates of the campaign will be up for grabs.

Tennessee's 58 delegates are the third-most available on Super Tuesday after Texas and Georgia. Candidates must earn at least 20 percent of the vote to earn a proportional share.

Haslam's endorsement comes two days after the end of the state's early voting period that saw record turnout, with two out of every three ballots being cast on the Republican side.

Haslam was coy when asked by reporters earlier this week whether he could support Donald Trump if the current GOP front-runner becomes the nominee, saying he wanted to let the primary process play out first.

"I want to remind everybody the issues we have are complex and difficult, and we really need folks that propose actual answers to that, instead of just frustration with what's happening now," Haslam said.

"We need to have people who are talking about here's exactly what I would do differently," he said. "That's what's important as we go vote."

Tennessee Republicans have shied away from establishment candidates in the last two primaries, choosing former Pennsylvania Sen. Rick Santorum in 2012 and former Arkansas Gov. Mike Huckabee in 2008.

Haslam in 2012 endorsed former Massachusetts Gov. Mitt Romney, who ended up coming in 9 percentage points — and 10 delegates — behind Santorum in Tennessee's GOP primary.

Haslam's former economic development commissioner Bill Hagerty this week switched his support to Rubio after former Florida Gov. Jeb Bush dropped out. Hagerty was a top transition planner for the campaigns of both Romney in 2012 and Arizona Sen. John McCain in 2008.