McCain's relationship with the Latino community has been poisoned by the anti-immigrant Tancredo wing of the Republican party, but also by McCain himself. When he coauthored the McCain-Kennedy immigration bill, which would have provided a path to citizenship for 12 million illegals, many of them Latinos, he was cheered by the Latino community.
For a while it looked like he could have gotten more than the 40% of the Latino vote that Bush got in 2004. But when he rejected his own bill and said he would veto it if Congress passed it, the Latinos bailed on him. Four key swing states--Florida, Colorado, Nevada, and New Mexico--have large Latino populations and he has developed a profound weakness there that is probably too late to repair. Earlier this year when McCain was forced to make a choice--between the Tancredos and the Latinos--he chose the Tancredos and he has now discovered that you reap what you sow.
http://www.electoral-vote.com/Color me surprised - NOT!
(ETA:)
Hispanics turn cold shoulder to McCain:
http://www.politico.com/news/stories/1008/14444.html