President Obama will win reelection if the Republican nominee does not win back a significant share of Hispanic voters, the largest minority in the United States, with 21 million eligible to vote in November.

On the Bush campaign team in 2000, we knew we needed 40 percent of the Hispanic vote to win. We got 41. With the trending growth of the demographic, we quickly realized that if we maintained that same percentage in 2004, we would lose. We had to get 43 percent. We got 44. But four years later in 2008, with a record 9.6 million Hispanics voting, Barack Obama was preferred over John McCain, 67 percent to 31 percent.

While the president’s approval rating today among Hispanics has dropped to 49 percent, with 59 percent disapproving of the administration’s deportation policies, in a direct matchup with Mitt Romney, Obama wins 68 percent to 23 percent.

But the GOP candidates still have a chance to turn the tide at Wednesday’s “Meet the Candidates” forum, cosponsored by Miami-Dade College, the U.S. Hispanic Chamber of Commerce, and Univision. They have a chance if they can win back Los Desilusionados, “The Disappointed,” the roughly 50 percent of Hispanic voters who are disappointed by the president’s failure to deliver on his promises.

Pocketbook issues—jobs, education, health care, taxes, and the deficit—are the top concerns among Hispanic voters. The median net worth of Hispanic households has fallen more than in black and in white households. The decline in the housing market has hit Hispanics disproportionately hard. And unemployment among Hispanics remains well above the national average.

Republicans can and should do well with Hispanic voters: 35 percent self-identify as conservative; only 28 percent call themselves liberal. Messages that focus on values, family, and patriotism resonate. So, too, do strong economic policies. Hispanics are less likely than any other group, and the population as a whole, to agree with class-conflict messaging. In fact a large percentage of the Hispanic population perceive themselves as being part of the top 1 percent of Americans economically.

While economic issues are the priority for Hispanics—whether of Mexican, Cuban, or Puerto Rican heritage—and should be if the election remains a referendum on the president’s job performance, the GOP candidates’ tone on immigration colors perceptions of the party.

Recognizing early on that Rick Perry, at least on paper, was a significant threat to his candidacy, Mitt Romney aggressively attacked the Texas governor for an enlightened policy that allows children of illegal immigrants who have resided in Texas for three years, contributing to the tax base, and who commit to complete citizenship requirements, to pay in-state college tuition rates. The 2001 legislation was backed with nearly unanimous bipartisan—and veto-proof—support by the Texas legislature in 2001. Though Perry inartfully articulated a defense of the Texas law, similar in name to the failed federal DREAM Act, which provided a path to citizenship for individuals (and their families by petition) through college attendance or military service, the damage was done. With his nativist rhetoric, Romney helped to destroy the Perry campaign, and possibly his own in the long term, with Newt Gingrich taking a more moderate position on resolving illegal immigration.

Here’s the harsh reality: unless Republicans win enough support from Hispanic voters, it doesn’t matter what happens in the rest of the campaign. The GOP will lose.

It is a danger to assume any group votes as a monolithic bloc, but Hispanic voters have been courted and disappointed by both parties. If the GOP candidate decides to make a real effort to reach out to Los Desilusionados and make a case that President Obama does not deserve their vote again, beginning in the crucial battleground state of Florida, Hispanic voters may return home to the Republican Party. And a Republican will return to the White House.