The United States Senate has voted in favour of lifting a 40-year-old ban on Americans travelling to Cuba.
The White House says tourism will prop up Castro
In a major rebuff to President George W Bush, Senators voted 59 to 36 to bar the use of government money to enforce the travel restrictions.
The vote follows a similar move by the House of Representatives last month.
The White House has said Mr Bush will veto the bill if it is backed by Congress.
Both houses of Congress are, nonetheless, controlled by Mr Bush's own party, the Republicans.
The BBC's Justin Webb in Washington says the Senate vote is a severe blow to the White House's authority, forcing Mr Bush into a damaging public row with some of the most significant figures in his party.
Senators called for the travel restrictions to be lifted, saying it made no sense to ban Americans from visiting Cuba while they were allowed to go to countries like North Korea.
Republican Senator Mike Enzi said: "For 40 years we've said 'sanctions', and for 40 years it hasn't worked," referring to the failure of the ban to unseat Cuban leader Fidel Castro.
But the White House said it was premature to lift the ban.
"The administration believes that it is essential to maintain sanctions and travel restrictions to deny economic resources to the brutal Castro regime," it said in a statement.
Mr Bush has his eye on anti-Castro Cuban American voters in the key state of Florida in next year's presidential election, but many senators believe that is too narrow a view, our correspondent says.
About 160,000 Americans visited Cuba legally last year, as members of groups with special dispensation or travelling via Canada and Mexico.
Cuba has said it expects about a million Americans to visit in the first year if the ban is lifted.
The Senate vote was welcomed by the Cuban Government, which hopes American tourism will boost hard currency earnings to pay for food imports.
"This is further evidence that both chambers of the US Congress and a majority of the US people favour lifting the
travel ban," said Foreign Minister Felipe Perez Roque.
"I wonder what new trick Washington will invent to stop
this becoming law," he added.