Rubio, R-Fla., praised the way Trump motivated millions of people to vote Republican for the first time and predicted Trump could have a second act in the White House.
"If he runs in 2024, he'll certainly be the front-runner and will probably be the nominee," Rubio told congressional pool reporters Tuesday. "But again I'm still being presumptuous here, we're not even through with 2020.”
Republicans largely have stood with Trump as he contests Joe Biden's win in the 2020 election through various court challenges. Assuming Trump's legal battles fall short in changing the outcome of the election, the president would be eligible to run again for office in 2024.
Rubio is among a long list of Republicans -- including Vice President Mike Pence and even Don Trump Jr. -- who are expected to consider a run for the presidency, though on Wednesday the senator declined to comment on a 2024 bid for himself.
"We're not even through with 2020, there's a lot of other decisions to be made, so I haven't even -- honestly guys, no one can even start thinking about things like that until some period of time has elapsed," said Rubio, who will soon campaign in Georgia for the two senate run-offs elections.
Axios reported Tuesday that Trump is already mulling a possible 2024 run, signaling the president at least privately is accepting his loss in 2020.
Presidents have a two-term limit, but the terms do not need to be back-to-back.
Fox News' Paul Steinhauser contributed to this report.