Fidel Castro's crackdown on dissidents has taken momentum away from what had been a growing, bipartisan effort in Congress to ease four-decade-old U.S. sanctions.

Embargo opponents will continue to seek changes on grounds that Americans and ordinary Cubans are being punished, not Castro. Most admit, however, that their prospects are dim.

"The embargo is still a bad idea, but changing it isn't going to happen any time soon," said Rep. Charles Rangel, D-N.Y.

Even before the crackdown, the likelihood was small that sanctions woeatened to veto any bill to weaken it. He has strong support from anti-Castro Cuban-Americans in Florida, which could be pivotal in the 2004 elections, as it was in 2000.

In growing numbers, however, free-trade Republicans, mostly from farm states, have joined liberal Democrats in declaring the embargo a failure. They point out it has not forced Castro from power -- its goal -- but has denied Americans the freedom to do business or travel in Cuba.

Congress loosened the embargo in 2000 to allow sale of agricultural products on a cash-only basis. Rangel's proposals to end the embargo have gained support in yearly votes and failed last year by a 226-204 margin. More limited measures that effectively would end the travel ban have had strong support in the House and Senate.

Anti-embargo lawmakers believed their prospects were even better this year -- until Castro's crackdown.

With the world's attention diverted by the war in Iraq, Cuba sentenced 75 dissidents to prison terms this month ranging from 6 years to 28 years, charging they were working with the U.S. government to undermine the country's socialist system.

"The crackdown has perhaps clarified in some people's minds the true nature of the totalitarian regime," said Rep. Lincoln Diaz-Balart, R-Fla., a leading supporter of the embargo. Diaz-Balart sponsored a resolution condemning the crackdown, which the House approved 414-0 on April 8.

Rep. William Delahunt, D-Mass., was among embargo opponents who voted for the resolution. On the House floor, he spoke of two of those arrested as friends. "For me, this issue is more than political. It is personal," Delahunt said.

In an interview, he said he still opposes the embargo, but the momentum to end it has stalled. "Obviously, it's become more difficult," he said.

He said opponents of the sanctions may have to focus more on easing the travel ban instead of doing away with the embargo altogether. The travel ban limits trips to Cuba to specific categories of visitors, such as researchers and working journalists.

Last year, the House voted 262-167 on an amendment by Rep. Jeff Flake, R-Ariz., to block the travel ban as part of a Treasury spending bill that never passed. Flake said he plans to try to pass the same measure this year.

"We never embarked on this policy as a way to reward the Cuban government for good behavior," he said.

Flake said they don't believe Castro wants the travel ban eased, fearing the influence of American visitors to his island. Embargo opponents have often questioned whether Castro secretly favors the sanctions, which give him an excuse for his country's weak economy and earns him international sympathy.

"Anybody who really believes that Castro wants the whole embargo lifted has to wonder why every time we get closer, he pulls something like this," Flake said.

President Carter's hopes of normalizing U.S.-Cuban relations were followed by the 1980 Mariel exodus, in which Castro sent criminals and psychiatric patients to the United States along with thousands of other fleeing Cubans. President Clinton's reluctance to support a bill tightening the embargo ended when Cuba shot down two unarmed planes operated by the Miami-based Cuban-American Brothers to the Rescue in 1996.

But Rep. Ileana Ros-Lehtinen, an embargo supporter, said the crackdown shows opponents were wrong in believing that greater business and personal contacts between Cubans and Americans would help bring down Castro. Clinton had favored people-to-people exchanges with Cuba, but the Bush administration has placed greater restrictions on such contacts.

Ros-Lehtinen said she hopes the crackdown will help keep the embargo intact but isn't taking that for granted.

"At the end of the day," she said, "our best insurance policy is the veto pen of President George W.Bush."