To begin with Pearce already violates anti-immigration reform advocates’ admonition not to legalize those already here with his support of work permits. For those anti-reformers who insist on actual or “self-deportation” there is little to suggest they can win over Hispanic voters.
Moreover, traveling to meet every voter, providing oodles of constituent services and pitching in to help unload trucks (as the report notes) don’t make for a feasible campaign strategy for presidential candidates, senators (unless they are from a small state) and challengers who don’t yet have the benefit of doling out help to constituents.
It is also the case that for candidates seeking to represent a diverse ethnic electorate and urbanites, opposition to immigration reform may be a problem with non-Hispanic voters. As with gay marriage, opposition to some form of reasonable immigration reform can easily (sometimes justifiably) be transformed in the hands of a capable opponent into antipathy toward minorities and reactionary views in general.
And as the party at the national level moves steadily toward immigration reform, anti-immigration conservatives will find themselves more isolated and more easily characterized as extremists.
If one looks at conservative candidates (e.g. Sen. Marco Rubio (Fla.), Gov. Susana Martinez (N.M.)) who have won at the state level carrying a significant percentage of the Hispanic vote, you will see they have strong support for legal immigration and border security but also for some form of regularizing those here illegally. Yes, they also stay in touch with voters and, yes, they also try to gear their policy proposals toward middle- and lower-income voters, stressing education and upward mobility. But conservatives are kidding themselves if they think they can win national or statewide without changing their tune on immigration. As Rubio said, so long as they want to deport your grandmother, a Republican isn’t going to get a hearing with minority voters.