Aside from the former governor, the Senate bill is being supported by current Florida Gov. Charlie Crist, a Republican, and Senator Mel Martinez, a Cuban immigrant who is chairman of the Republican National Committee and has been intricately involved in crafting the immigration bill.
Martinez said on CNN Sunday that the immigration bill "could be the saving of the Republican Party, frankly."
David E. Johnson, a Florida-based Republican consultant, said Romney's immigration stance could harm his relationship with Florida lawmakers, including Bush, who has strongly signaled that Romney is his preferred candidate for president.
But the issue still may not be a "deal-breaker" for Bush, Johnson said. And any political harm could be outweighed by additional support he might receive from the party's conservative base, which is more skeptical of the immigration bill than the state's top GOP officials, he said.
"It will hurt him with the Bush people, but it won't hurt him too much with the rank and file," Johnson said. "People are disgusted with what's going on as far as immigration. There's a feeling that basically the party leadership is ignoring the rank and file."
Still, Florida Republicans -- with their relatively high proportion of Hispanics -- are more inclined than Republicans in other states to support a bill that would allow undocumented immigrants to achieve citizenship, said Rep. Lincoln Diaz-Balart, R-Fla.
Without naming names, Diaz-Balart said he's troubled with the "tone" being struck by several Republican presidential candidates.
"Hispanics are looking for sensitivity, and for people who are acting in a reasonable fashion, and are not succumbing to unfortunate instincts," said Diaz-Balart, a McCain supporter. "There are a number of worrisome overtones that we're hearing in this debate. I would hope that we would not hear them in the presidential campaign, but unfortunately we're already hearing them."
David Rivera, a Republican state representative from Miami, said he is still considering supporting Romney for president. But he said Romney's position on immigration gives him "pause" in making his choice, since he wants a candidate who appreciates the contributions made by both documented and undocumented immigrants.