Ramon Espinosa, File, Associated Press
In this Jan. 22, 2015 file photo, Cuban and U.S. flags stand before the start of a press conference on the sidelines of talks between the two nations in Havana, Cuba. Members of the U.S. Democratic congressional delegation to Cuba said on Tuesday, Feb. 17, 2015 the next round of negotiations on restoring full diplomatic ties with Cuba will take place in Washington next week.

HAVANA — A new round of negotiations to restore full diplomatic ties with Cuba will take place next week in Washington, according to a delegation of U.S. senators who said they were hopeful the two sides would reach a deal soon.

Mark Warner of Virginia, Claire McCaskill of Missouri and Amy Klobuchar of Minnesota made their first trip to Cuba over the weekend in support of a bill Klobuchar is sponsoring to lift the U.S. trade embargo on Cuba.

Teams of negotiators led by Assistant Secretary of State Roberta Jacobson and Cuba's top diplomat for U.S. affairs, Josefina Vidal, are working to resolve Cuban demands that include the easing of banking restrictions on its diplomats in the U.S. and limits on U.S. support for dissident groups that Cuba considers illegal.

The U.S. wants Cuba to eliminate some of the heavy security cordon around its interests section in Havana and allow unrestricted travel for its diplomats in Cuba, among other demands.

"We look with hope and expectations to the meetings next week in Washington between the Cuban government and the American State Department to make progress," Warner told reporters in Havana on Tuesday.

He did not say if he expected the pending issues to all be resolved in the coming round of talks but told a large group of reporters, most from Cuban state media, that diplomats often moved more slowly than politicians want. The next three to six months are a key window for progress in the normalization of ties between Cuba and the U.S., he said.

"Frankly I'm optimistic because the negotiators are two women and we know how to get things done," McCaskill said.

"We don't think any of these things are going to stall out the ability to get full diplomatic relations, hopefully soon."

Michael Weissenstein on Twitter: https://twitter.com/mweissenstein