SCOTTSDALE, Ariz. — Mitt Romney has a problem with Hispanics.

The presumptive Republican presidential nominee trails Democratic President Barack Obama among Hispanic voters by a ratio of better than 2-1, a deficit large enough to cost him the presidency as it did John McCain four years ago.

Some of his problem comes with the Republican brand, some through his own tough talk on illegal immigration during the Republican primaries. Either way, Romney has to find a way to close the gap or lose.

Among the options — a conservative version of immigration reform, an Hispanic running mate, and plenty of grassroots courting.

“It’s the most important swing voter group in the country,” said Republican pollster Whit Ayres.

That’s because the country’s demographics are changing. Republicans tend to win the majority of whites, but whites are shrinking as a percentage of the country, while Hispanics surge.

Ayres noted that McCain in 2008 won the same percentage of the white vote as Ronald Reagan did in 1980. But whites represented 88 percent of the vote in 1980; the representation was 74 percent in 2008. Reagan won handily. McCain lost.

At the same time, Hispanics surpassed African Americans as the country’s largest minority, and their share of the vote grew too.

Republicans fared well with George W. Bush, who backed immigration reform that would allow a path to citizenship for illegal immigrants already in the country.

He took 44 percent of the Hispanic vote in 2004, helping him win a close re-election. By 2006, the Republican Party enjoyed its best standing ever, as 49 percent of Hispanics called themselves Democrats and 28 percent called themselves Republican, a 21-point deficit measured by the non-partisan Pew Hispanic Center.

Then Republicans helped kill immigration reform. They cheered as Arizona adopted a get-tough law. By last December, 67 percent of Hispanics called themselves Democrats and 20 percent called themselves Republican, a 47-point deficit.

Romney jumped in during the primaries, eager to prove his conservative bona fides. Among other things, he ripped Gov. Rick Perry of Texas for supporting in-state tuition for the Texas children of illegal immigrants.

By last week he trailed Obama among Hispanic voters 67-27 in a new Pew Research Center survey.