An effort to harshly tighten restrictions on Cuban Americans’ travel and remittances to Cuba has come down to last-ditch negotiations in Congress over a huge government spending bill.

It remains unclear exactly how the restrictions would be tightened if a rider attached by Rep. Mario Diaz-Balart to the spending bill is approved by Congress, as members of Congress and news reports are predicting.

Congressional aides say travel and remittances would be returned to the level set by President George W. Bush in 2008: only one trip every three years for “family reunifications,” a cap on remittances of $1,200 per year and a tighter definition of “family.” Other analysts of sanctions on Cuba say travel and remittances would return to the slightly easier Clinton-era level, which allowed one trip per year and more cash assistance.

But it was clear that Diaz-Balart’s rider was worrying supporters of President Barack Obama’s decision in 2009 to lift virtually all restrictions on Cuban American travel and remittances to the island.

“My concern is that this [measure] is very much alive,” said Rep. José E. Serrano, a New York Democrat who has fought for years to relax or abolish all U.S. sanctions on the Cuban government.

“Some Democrats backing the administration policy [on Cuba travel] seemed resigned to defeat,” noted an Associated Press story on the closed-door negotiations over the massive compromise spending bill.

Some Democrats in the House and Senate don’t want to be seen favoring increased travel to Cuba at a time when Havana has been cracking down on dissidents and is holding U.S. government contractor Alan Gross in prison, said a Republican senator’s aide.

“Alan Gross and beatings of dissidents make it difficult for the average member of Congress to endorse gestures to Cuba,” said the staffer, who asked for anonymity because he wasn’t authorized to comment on the issue.

Gross is serving a 15-year sentence on charges of violating Cuba’s national security laws by delivering a satellite telephone to members of the island’s Jewish community so they could have better access to the Internet.

Diaz-Balart’s rider must survive the tough negotiations between the Republican-controlled House and Democratic-controlled Senate, expected to be concluded before the end of the year.

Obama also has threatened to veto any rollback of his Cuba policies.

Some of the more controversial riders on the spending bill already had been dropped by Tuesday as the negotiations moved forward. But Senate Majority Leader Harry Reid said Tuesday that “some major issues [remain] to be resolved, some foreign policy issues, including Cuba.”

White House Press Secretary Jay Carney said there remains “issues to be resolved with the spending bill,” including “attempts to attach riders on our foreign policy goals, the environment and other areas.”

Diaz-Balart’s measure was approved by a House committee this summer as a rider to a Treasury spending bill that was later rolled with eight other spending bills into the one massive measure now under negotiation.

Legal travel to the island by Cuban Americans exploded after Obama lifted the restrictions in 2009, although many Cuban Americans had been going to the island illegally through third countries.