WASHINGTON -- President Obama's decision in April to lift the limit on visits by Cuban Americans to their homeland was seen by some as a sign that the embargo, centerpiece of U.S. efforts to isolate the island, might be nearing its final days.

Don't count on it.

The president can weaken the embargo, but only Congress can rescind it. Embargo supporters in both houses, including Florida lawmakers from each party, remain confident they have the votes.

But something more nuanced is happening, a slow erosion:

• Miami Herald reporters visiting the island found that, embargo or no embargo, huge stockpiles of American-made goods are finding their way to Cuba -- sometimes legally, often not. From sunglasses to jetliners, if it's made here, you can probably find it there, although often at an exorbitant price.

Loopholes carved into the embargo in recent years have helped make the United States Cuba's top supplier of food and agricultural products and its fifth-largest trading partner.

• A persistent campaign by farm-state Republicans and business interests to junk the embargo has shifted its focus to chipping away at it piece by piece.

Their probable next target: the rule that prevents Americans not of Cuban descent from traveling to Cuba as tourists. Longtime opponents of the embargo have filed three bills this year that would do just that. Advocates insist the idea has gained traction -- and the backing of a diverse coalition of groups ranging from the American Farm Bureau to the U.S. Chamber of Commerce to Human Rights Watch.

``The theory is that travel is the thread that will unravel the whole sweater of the embargo,'' said Dan Erickson, a senior associate at the Inter-American Dialogue and author of The Cuba Wars: Fidel Castro, the United States, and the Next Revolution.

Embargo supporters say the same people have tried the same thing before and failed.

• The network of ``mules'' who illegally sneak goods or money into Cuba, often concealed on their bodies, has exploded since 2004, when the Bush administration tightened the screws on delivering goods to Cuba. Armando Garcia, president of Marazul Charters, which flies to Cuba, called it a ``huge parallel industry.'' Serafín Blanco, who runs a store in Hialeah that caters to exiles, said he can tell who is a mule by what items they buy and how many.

• Hard-line older Cuban exiles who have applauded past moves to bolster the embargo are becoming a smaller segment of the Cuban-American community. They still have clout -- witness last year's reelection of embargo champions Lincoln Diaz-Balart and his brother Mario to Congress despite formidable opposition -- but their ability to swing Florida's 27 electoral votes may be waning.

Some of those aging exiles are now taking advantage of Obama's olive branch to the island to go home for a visit. Among recent travelers: Nildo Herrera, who wore five hats as he waited in the terminal to board a Cuba-bound plane at Miami International Airport.

``One is for my grandson, another for my son, and the rest for other relatives,'' said the 75-year-old from Hialeah.

WAITING FOR CUBA

There is anecdotal evidence that the administration is allowing greater academic and cultural travel to Cuba, said Phil Peters, a Cuba analyst at the Lexington Institute in Arlington, Va., and a supporter of lifting the embargo.