– Marco Rubio said that if someone wants to be president, they should fully commit to just that, adding that candidates shouldn't try to hold their congressional seats while pursuing the White House.
The Florida Republican said in an interview that aired Sunday on ABC that, should he decide to launch a 2016 campaign, he won't run simultaneously for re-election for his seat in the U.S. Senate.
"I believe that if you want to be president of the United States, you run for president," he said. "You don't run for president with some eject button in the cockpit that allows you to go on an exit ramp if it doesn't work out."
Rubio also told ABC's Jonathan Karl that said he's ready to be commander in chief, "but I think that's true for multiple other people that would want to run."
Rubio has noted that Florida law prohibits candidates from being on the ballot for two offices, a rule he described as "the right law."
Past White House hopefuls have run for two offices at once, and the next group of presidential candidates will probably have to make the same judgment.
Kentucky, for example, has a similar rule to Florida's, but allies of Sen. Rand Paul, another potential 2016-er, in the state's GOP-controlled Senate passed a bill that would allow a candidate to simultaneously seek more than one office.
Rubio gives Clinton an "F" at State
Rubio's comments come two days after he made his first visit to New Hampshire, a key primary state, to talk to Republicans at the Granite State's Freedom Founders dinner. In his speech, Rubio took an apparent shot at a potential 2016 presidential opponent: Hillary Clinton.
Although not referring to Clinton by name, Rubio said: "They're threatening to nominate someone now who wants to take us to the past, to an era that is gone and is never coming back. The 20th century is gone. We live in the 21st century, a time of extraordinary challenges but also extraordinary opportunities. And that's where our party must step in."
He again leveled heavy criticism at Clinton on Sunday, telling ABC he thought American's former top diplomat deserved an "F" for her tenure at the State Department.
"I'm sure she's going to go out bragging about her time in the State Department. She's also going to have to be held accountable for its failures, whether it's the failed reset with Russia or the failure in Benghazi that actually cost lives," he said.."If you look at the diplomacy that was pursued in her time in the State Department, it has failed everywhere in the world," Rubio added.
Rubio once led the pack in a list of Republicans considering a run for the GOP presidential nomination in 2016. But in a CNN/ORC International survey released this week, only 6% of Republicans picked Rubio as their favorite in the next presidential race.
But despite his falling popularity in recent surveys, Rubio said he doesn't pay much attention to the polls.
CNN's Greg Clary and Ashley Killough contributed to this report.