Mickey Kaus has a post on Chris Cannon being defeated in Utah, headed "Comprehensivist Down!" which says in part that:

And Cannon lost by a large margin (60-40) primarily because he "failed to generate the kind of [Republican primary] turnout typically enjoyed by House incumbents." ...

Hmm. As if by eerie coincidence, John McCain has been having trouble generating the kind of popularity among Republicans typically enjoyed by Republican presidential candidates! And he's also been pushing "comprehensive" reform of late, potentially winning Latino support but further jeopardizing his GOP support. Kausfiles notes that there are more Republicans than Latinos. If McCain win's an extra 10% of Latino voters but loses an extra 10% of Republican voters, he loses, right? Maybe on his forthcoming trip to Mexico he will do the math. ...

Simple arithmetic. About half of all American voters vote Republican. If McCain loses ten percent of those, he's toast. Only a small fraction of the population is Hispanic, many of them are immigrants and aren't allowed  to vote, of those who do vote, the great majority vote Democratic. Even if McCain does better than Bush ever did among Hispanics, he still loses.

And if McCain thinks he can find votes in Mexico, he's sadly mistaken.