Washington, January 20 (RHC)-- President Obama will tell members of Congress at tonight’s State of the Union he has done all he can do to normalize relations with Cuba and only they can lift the 50-year-old blockade, an official source told ABC News.

The president will say it's the right thing to do and will make his case again to the U.S. people that the blockade is a failed policy and that it's time to engage Cuba.

The first congressional delegation since the announcement on December 17th to reset relations between the two countries, locked in a cold war for five decades, met with Cuban officials Monday to discuss the next steps.

“Fifty-four years of policy was changed overnight,” Sen. Patrick Leahy, a Democrat from Vermont, said, referring to Obama’s executive order at a news conference capping off their visit. “It was a remarkable and I believe, long overdue event.”

Sen. Dick Durban, Democrat from Illinois, one of six congressional delegates who came to Cuba this week, said: “I think we can put 50 years of the Cold War behind us in Cuba and move forward in a better way to make the relationship stronger.”

“It’s not going to happen quickly,” he stated. “I don't believe it will.  It takes some time.  In the Senate for example, with votes we are going to find members coming forward on both sides. There was a time, not that many years ago, when 60-plus members of the Senate, in both political parties, said let's expand agricultural trade with Cuba.”