(FORTUNE Magazine) – Forty-two years is an awfully long time to hold a grudge, but that's how long the U.S. has shunned commerce with Cuba. Forgiveness, however, may finally be around the corner, as a diverse group of business interests--from automakers to airlines--are pushing to end the embargo.

The motivation: With 11 million citizens 90 miles from Florida, Cuba is a multibillion-dollar market waiting to happen. "All sorts of groups are beginning to see the Cuban embargo from an America First perspective, and that's what's new," says Sally Grooms Cowal, a former top Latin America advisor to the first President Bush who now heads the anti-embargo Cuba Policy Foundation in D.C.

Some sectors like agriculture have long opposed sanctions on economic grounds. (Cuba was once a prime purchaser of U.S. grains.) Now, broader-based organizations, including the U.S. Chamber of Commerce, have joined agricultural giant Cargill and the American Farm Bureau Federation in the anti-embargo lobby. Says Chamber President Tom Donohue, who visited Cuba not long ago: "All our competitors are down there doing business--the Japanese, the Europeans. Every time a contract is signed, our allies have a cocktail party to celebrate our stupidity."

Donohue speaks for more than three million businesses and 830 trade associations. The auto, pharmaceuticals, and tourist industries (including hotel company Marriott) all favor more trade with our nearby neighbor. Donohue argues that the embargo has clearly failed: The 75-year-old Fidel Castro is still in power, and Cuba, which could be a prosperous Caribbean playground, is impoverished. According to the U.S.-Cuba Trade and Economic Council, the average Cuban earns only $13 a month, and the country's GDP is basically flat. Castro's heir apparent, his 71-year-old brother, Raul, is more pro-Western. Unless the U.S. moves quickly, Donohue warns, foreign companies will swoop in and dominate post-Fidel Cuba.

In March, Donohue gained an ally, USA Engage, a multi-industry, 674-member affiliate of the country's oldest free-trade advocacy group, the National Foreign Trade Council. USA Engage's members range from insurance and aerospace companies to furniture and semiconductor manufacturers. Politicians are also pressing the case, and an increasing number of them are of the once unswervingly anti-communist and pro-embargo Republican variety. George Ryan, the Republican governor of Illinois, led a delegation of executives to Havana this year to spotlight his disdain for sanctions. Mike Huckabee, the GOP governor of Arkansas, wrote to President Bush seeking action against the embargo. Lawmakers in Illinois, Arkansas, Louisiana, and Texas have approved resolutions calling for a partial or total end to the embargo. California and Georgia have resolutions pending. In Congress, a bipartisan group of 34 members of the House that calls itself the Cuba Working Group has vowed to fight the embargo.

They have already achieved some success. Congress eased the embargo two years ago to permit the sale of food and medicine, and may weaken it again soon. Last July the House voted overwhelmingly to end funding for the enforcement of the travel ban to Cuba, and in December the Senate voted to allow U.S. companies to finance sales to Cuba, which now can be completed only in cash.

While momentum is strong, neither bill is likely to reach the President's desk this year. The anti-Castro votes of the Cuban community in Miami are vital to the reelection prospects of President Bush's younger brother, Governor Jeb Bush, and the President's own close call in Florida will make him wary of defying so large a voting bloc. Still, with much of American industry backing Cuban trade, a year or two out there may be reason for members of the anti-embargo lobby to celebrate with a stogie. Cuban, of course.