Senate Majority Leader Mitch McConnell said on Sunday that he thinks Congress will ultimately block whoever President Obama nominates to be ambassador to Cuba.

The Kentucky Republican said on "Fox News Sunday" that the Senate is not likely to confirm any U.S. ambassador to Cuba nominated by Obama as part of the president's attempts to restore full diplomatic and economic ties with the country.

"This president has been involved in ... talking to a lot of countries: talk, talk, talk. And Cuba is a good example. He thinks that simply by engaging with them we get a positive result," McConnell said, adding, "I don't see any indication that Cubans are going to change their behavior. What are we getting as a result of normalization of relations?"

In December, Obama announced his plan to use executive powers to normalize relations with Havana after a five-decade interruption.

Part of that plan has so far included establishing diplomatic relations, allowing some forms of travel from the U.S. to Cuba, lifting bans on the trade of some goods and services, and increasing the limit on remittances to Cubans from people living in the U.S., reports Reuters.

Cuba was also removed from the U.S. list of state sponsors of terrorism, and an agreement was made for embassies to be re-opened in both countries on July 20.

In terms of improving relations with Cuba, the executive branch has now done nearly all it has the power to do.

Obama still has to nominate an ambassador, but knowing the opposition he faces, a State Department official said last week that he plans to take his time, according to the Washington Post. One senator has the ability to significantly stall the appointment of any Obama nominee for ambassador, but an ambassador isn't necessarily needed, one top Democrat told Politico. The White House said this month that Jeffrey DeLaurentis, who has headed the diplomatic mission in Havana since last summer, will continue to work as the "senior most official" at the U.S. Embassy.

One of the major obstacles preventing complete normalization of relations is an economic embargo still in place against Cuba - which the Castro regime has said must be removed for relations to be fully restored.

Only the Republican-led Congress has the power to remove the embargo, and so far, it has refused to honor Obama's requests for removal.

"There are sanction that were imposed by Congress," McConnell said. "I think the administration will have a hard time getting those removed. This is a policy that there is substantial opposition to in Congress."

Many Republicans are against Obama's diplomatic efforts, claiming that they only prop up a Communist regime still involved in sponsoring terrorism and human rights violations.

Being that two of the Republican senators most opposed to Obama's rapprochement with Cuba, Marco Rubio and Ted Cruz, are both Cuban-Americans running for president, the issue is sure to meet stronger resistance as the 2016 election nears.

The White House responded to McConnell's remarks on Monday: "I think that that's the kind of reflexive opposition to you know, anything that the president proposes, that is a hallmark - has been a hallmark of at least this Republican Congress," White House press secretary Josh Earnest said Monday, according to Roll Call. "The irony here is there actually is some bipartisan support for the Cuba policy that the president announced at the end of last year."