President Obama on Wednesday announced a major step toward "diplomatic relations with the Republic of Cuba" by saying the U.S. and Cuba would reopen embassies in each other's countries.

"This is a historic step forward in our efforts to normalize relations with the Cuban government and people and begin a new chapter with our neighbors in the Americas," Obama said in a statement in the Rose Garden with Vice President Joe Biden at his side.

"This is what change looks like," he said later in his remarks, referring Secretary of State John Kerry's plans to travel to Cuba later this summer and hoist the American flag above the U.S. embassy in Havana.

When the U.S. shuttered its embassy on the island in 1961, the year Obama was born, "I don't think anyone expected that it would take more than half a century before it reopened."

Obama said that even though the two countries have very real differences, "sometimes we allow ourselves to be trapped by a certain way of doing things." He said that the United States clung "to a policy that clearly was not working."

"Our efforts to isolate Cuba, despite good intentions, often had the opposite effect," the president said. "We don't have to be imprisoned by the past. When something isn't working, we can and will change."

The opening of embassies is a step that was made possible by the U.S. decision to take Cuba off the list of terrorist-sponsoring nations, a step Cuba was demanding before it could agree to Obama's push for official embassies.

Obama's moves have led to fierce criticism from Republicans and even some Democrats, who say Obama is giving Cuba several concessions while Cuba has not indicated it would return fugitives to the U.S., ease its crackdown on pro-democracy dissidents, or take steps toward democratic reforms.

For those reasons, some congressional Republicans said even before Obama spoke that they will block efforts to install an ambassador. Sen. Marco Rubio, R-Fla., said he would hold up any nominee until President Raul Castro stops imprisoning political opponents.

And House Speaker John Boehner, R-Ohio, stressed Wednesday that Obama's moves are only benefitting the Cuban government, not the Cuban people.

"The Obama administration is handing the Castros a lifetime dream of legitimacy without getting a thing for the Cuban people being oppressed by this brutal communist dictatorship," he said. "As I've said before, relations with the Castro regime should not be revisited, let alone normalized, until Cubans enjoy freedom — and not one second sooner."

But Obama rejected those comments and said the U.S. should push further to lift the travel embargo against Cuba. "After all, why should Washington stand in the way of our own people?" he said.