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Mitt Romney has a problem with Latino voters - and now even his supporters admit it.

Former Florida Gov. Jeb Bush, who just two days ago endorsed Romney, told reporters in San Antonio Thursday that Romney needs to "change the tone" with Latinos away from immigration issues and more towards areas such as education, small business development, and social issues, noting that the GOP frontrunner can do "quite well" if he does.

"He's embraced education reform, which to me is the most important, aspirational set of policies. If you advocate reform, you're going to get more people a chance to be successful. He has a pro-family perspective that I think is important and has been embraced by Latino families across the country. He has an agenda to embrace small businesses and I think emphasizing that in terms of regulatory reform, tax reform, will help with Latino voters. His own life experience is one that I think can be helpful. But, he's got to change the tone a bit, that's all - and I think a lot of the things, the emphasis," Bush said.

"I don't know anybody that doesn't think the border needs to be controlled, but immigration issues are a lot more than just that, so I'm confident that without violating principal he will be able to broaden the conversation and I think he can do quite well among Latino voters," he added.

As we covered earlier this week, Romney during the primary has made a series of comments that have alienated Latinos, the nation's fastest-growing voting bloc. The former Massachusetts governor vowed to veto the DREAM Act - the Democrats' measure to provide a path to citizenship for some children of undocumented immigrants who attend college or serve in the military; he praised Arizona's strict immigration law that ordered immigrants to carry their registration documents at all times and mandated that police question them if there was reason to suspect that they were in the country illegally, calling the measure "a model"; he touted the endorsement of Kansas Secretary of State Kris Kobach, the author of the controversial law; he outlined an immigration policy based on the notion of "self-deportation"; and, when pressed about the fact that a lawn-care company he once used had employed undocumented immigrants, he noted that he told the company, "I'm running for office for Pete's sake - I can't have illegals."

Polls reveal the damage done. According to a late January poll conducted by Latino Decisions for ABC News and Univision, 67 percent of Latinos said they would back President Obama in a matchup against Romney, who only earned 25 percent of their support. 41 percent of Latinos nationwide said they have a somewhat unfavorable or very unfavorable view of Romney. A whopping 72 percent of Latinos said the Republican candidates in the primary either don't care too much about Latinos or are being outright hostile towards Latinos.

One move that might help Romney among Latinos would be to select Marco Rubio, the freshman Florida senator, as his running mate. In an interview with the Pittsburgh Tribune-Review, Bush said Rubio would be Romney's best pick for the number-two slot on the ticket, praising him as "dynamic, joyful, disciplined and principled" and "the best orator of American politics today." Rubio would undoubtedly help Romney's case to Latinos in Florida. The Latino Decisions poll from January revealed that 60 percent of Latino Republicans in the Sunshine State would be much more likely to vote Republican in November if Rubio were added to the GOP ticket. Nationwide the Rubio bounce among Latinos would be less impressive, with only 13 percent of Latino Republicans more likely to vote for a ticket with Rubio on it.

Bush endorsed Romney on Wednesday, a day after Romney cruised to a lopsided victory in the Illinois primary over rival Rick Santorum. After Romney's impressive win, Bush said that it was "time for Republicans to unite behind Romney and take our message of fiscal conservatism and job creation to all voters this fall."

Unfortunately for Romney, Bush's endorsement was drowned out by comments Romney's strategist Eric Fehrnstrom made that, come the general election, "everything changes, it's almost like an Etch A Sketch - you can kind of shake it up and restart all over again."

"If you read the whole thing of what the guy said, it's pretty clear to me that what he was talking about was that the campaign will re-focus its efforts on the general election. I don't think he was saying that the candidate will erase his beliefs and create a whole new set of them," Bush said.

Bush, addressing fears of a drawn-out primary if Santorum and Newt Gingrich refuse to drop out of the race, said that "they have every right to run and if they see that they have a chance in winning, why not keep going? But at some point, it could become a problem because you know, the convention is in August. You have September and October, basically 70 days to run against a well-oiled machine."

"So we do need to unite behind our candidate sooner rather than later for sure," he noted.

Bush, the brother of former President George W. Bush, was in San Antonio Thursday to deliver a lecture on climate change and he spoke to reporters after the lecture.

Matthew Jaffe is covering the 2012 campaign for ABC News and Univision.