Florida’s Senator Marco Rubio issued a sharp rebuke Wednesday afternoon to President Barack Obama’s decision to negotiate a prisoner swap with Cuba and restore diplomatic relations with the communist regime.

Rubio, the son of Cuban immigrants who left the island just before the Castro revolution in 1959, said while he’s glad imprisoned American Alan Gross is now free, he believes the U.S. brokered a bad deal with Cuba, should not have negotiated a prisoner swap with the dictatorial regime, and should have demanded more concessions.

“This president is the single worst negotiator we have had in the White House in my lifetime, who has basically given the Cuban government everything it asks for and receive no assurances of any advances in democracy and freedom in return,” Rubio said in a press conference Wednesday.

He said he would “make every effort” to use his role as chairman of the Senate Foreign Relations subcommittee in the new Congress to block Obama’s actions regarding Cuba.

“Appeasing the Castro brothers will only cause other tyrants from Caracas to Tehran to Pyongyang to see that they can take advantage of President Obama’s naiveté during his final two years in office,” he said in a statement. “As a result, America will be less safe as a result of the President’s change in policy.”

President Obama said the U.S. agreed to release three Cuban spies in exchange for a U.S. intelligence asset who has been imprisoned for nearly 20 years for spying on Cuba. He said Gross, an aid worker who had been imprisoned for five years, was released separately by President Raul Castro under “humanitarian grounds.” The deal came about in secret meetings between US and Cuban officials held in Canada since the spring of 2013, and at the Vatican. Obama also declared the new deal marks the beginning of “a new approach” with relations with Cuba that expands economic and easing travel ties with Cuba while opening up a U.S. embassy in Havana.

“These 50 years have shown that isolation has not worked,” Obama said in his announcement Wednesday.

Rubio said the problem isn’t the economic and travel measures, the problem is the administration should have demanded more in return.

“There is no concessions on freedom of speech, no concessions on elections, no concessions on the freedoms of having alternative political parties, no concessions on ever having elections or anything of that matter,” Rubio said on Fox News.  “What democratic concessions? And this notion that somehow being able to travel more to Cuba, to send more money to Cuba, and sell more consumer products in Cuba, the idea that that is going to lead to some democratic opening is absurd.”

Obama said he remains seriously concerned about human rights violations in Cuba, but he did not believe the current isolation policy was going to change the government’s behavior.   

“I do not believe we can keep doing the same thing for over five decades and expect a different result,” Obama said, adding that he hopes these measures will renew an “honest and serious debate about lifting the embargo” in Congress.

However, Rubio, a powerful Republican in the incoming GOP-majority U.S. Senate, says debate aside, there is no support in the Senate for lifting the Cuban embargo and said the Obama administration has now undermined the purpose of the embargo in the first place.

“I think the embargo is misunderstood. The embargo is not there to punish Cuba or even the Cuban government. The embargo serves as leverage,” explained Rubio, who said the Obama administration. “The embargo can be lifted tomorrow if Cuba opens up democratically, that’s all they have to do for the embargo to be lifted – they have to become a democracy.”

But Republican Senator Jeff Flake of Arizona said Rubio was wrong to view the embargo that way.

“The policy that we have had in place for the past 50 years has done more, in my view, and many view,” he said, “to keep the Castro regime in power than anything we could have done.”