Sen. Marco Rubio and former Gov. Jeb Bush are urging the Republican candidates to be careful.

“There are those among us that have used rhetoric that is harsh and intolerable and inexcusable," Rubio cautioned last week at the Republican Hispanic Leadership Network, which released a poll showing Obama’s Latino support is slipping.

The Pew Hispanic Center has found a similar, downward trend nationwide.

But a Florida survey — Univision News/ABC/Latino Decisions — last week found Obama had a 10-percentage point lead over Romney. A Quinnipiac poll of registered voters — as opposed to likely voters — released days earlier showed Obama winning Hispanics compared to Romney by 54-35.

Earlier this month, Quinnipiac found Obama was essentially tied with Romney, 46-45.

Those surveys polled registered voters. The Miami Herald’s Mason-Dixon poll, which showed Romney doing well, surveyed self-described likely voters. But the 16-percentage point lead isn’t much, considering the 10 percent error margin for the sample of Hispanics (about the same for the Quinnipiac polls).

One reason Romney might be doing well is that he is advertising on Spanish-language television and radio. Obama isn’t right now.

But Obama is getting help from the unlikeliest of places: conservative Republicans like state Sen. Alan Hays of Umatilla, who recently complained that “there are many Hispanic-speaking people in Florida that are not legal.”

Romney avoids talk like that, but he supports “self-deportation,” which Democrats say is code for making life tougher for people who look or sound like immigrants. If they can make that case during the campaign, it would be a dream for Obama come November.

Miami Herald Political Writer Marc Caputo begins a weekly column today about all things political. It will appear every Monday.