Obama shouldn't have ruled out troops: Rubio

America must do whatever is necessary, including deploying U.S. ground troops, to defeat Islamic State militants who are leading insurgencies in Syria and Iraq, Sen. Marco Rubio told CNBC on Thursday.

The Florida Republican, a potential 2016 presidential candidate, said President Barack Obama should not have ruled out ground troops in his address Wednesday night.

"We don't want to have American ground troops there. That possibility exists that if all other things fails, at least at the special operations level, it may require that at some point," Rubio said in a "Squawk Box" interview.

In his speech to the nation, the president announced an expanded military campaign against Islamic State militants, including American airstrikes in Syria. But he said it would be different than the wars in Iraq and Afghanistan because it won't involve U.S. ground troops.

Read MoreObama: 'Systematic campaign' against IS

Obama did acknowledge this counterterrorism effort could take years, which could mean the next president might be inheriting a military operation.

If Rubio were to run for the presidency and win, he may be the one to take the reigns from Obama.

Less than two weeks ago, Obama had said at a press conference: "We don't have a strategy yet."

Rubio was highly critical of the president's delay in addressing and formulating a plan to deal with the Islamic State threat. But the senator said he'd vote "yes" if Obama were to bring a credible plan of action to Congress.

He also said the president has the authority to act without approval from lawmakers.

—By CNBC's Matthew J. Belvedere

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