From [1]:

Los Angeles Mayor Antonio Villaraigosa, a Democrat, plans to dig into Mitt Romney in a speech on immigration reform Wednesday, when he will call the candidate's rhetoric and anti-immigrant endorsers "beyond the pale."

"For the first time in modern memory, a major political party is poised to nominate a presidential candidate who has abandoned immigration reform and instead advocates self-deportation," Villaraigosa will say in a speech to the National Association of Latino Elected Officials, according to prepared remarks. The speech also includes pressing for immigration reform and a second term for President Barack Obama.

...Obama told Hispanic media outlets in November that his campaign won't need to run negative "character assassinations" to win among Latinos, as he did handily in 2008. "We may just run clips of the Republican debates verbatim," he said.

...According to the prepared remarks, Villaraigosa will say, "We have a candidate who on Martin Luther King Day, a day celebrating racial reconciliation, had the architect of Arizona and Alabama's draconian anti-immigration laws campaign for him." (note: a reference to Kris Kobach

First, given things like this, it's an open question whether Villaraigosa's use of "beyond the pale" is a racist dog whistle of some kind.

In any case, what the Romney campaign should do in cases like this is to discredit those making such remarks. In the case of Antonio Villaraigosa that should be easy given his radical background; see the dozens of posts at that link.

Yet, I don't expect the Romney campaign to do that. If conservatives in general weren't what they are, Villaraigosa wouldn't have become mayor in the first place.

Instead, he became mayor and remains presented as credible by the media due to a combination of failings by many of those who do or who should oppose him. Those failings are in three main areas:

1. Incompetence: failing to make Villaraigosa a liability to the Democrats and the media;

2. Corruption: allowing massive immigration and thereby building a power base for those like Villaraigosa (see fiscal con);

3. Lack of patriotism: particularly the self-described "patriots" in the Tea Parties who turn their backs on Los Angeles and California in general because they're "librul".

In the general case, it would be very easy to discredit almost all supporters of illegal or massive immigration because they argue for something unworkable and they continually mislead using bogus talking points. Doing that would take much of the bite out of speeches like the above, yet neither the affected campaigns nor their supporters seem to be willing or able to help out.

Note also that Villaraigosa will be speaking to NALEO, a group that has a direct albeit minor link to the Mexican government. Don't expect to hear much about that either.

UPDATE: Either I'm misreading this, or someone at ABC News is catching on to how fake Villaraigosa is (link):

"We know that the reason we came here was because this was the place that embraced us. This was the place that said, 'If you work hard, and you play by the rules and believe in this great country, you will be rewarded.' We love that America," the California-born Democrat said.

Villaraigosa's quote sounds like he's an immigrant, despite being born here. He and NALEO are also very strong supporters of illegal immigration, something where people don't "play by the rules".

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[1] huffingtonpost.com/2012/02/08/
mitt-romney-immigration-antonio-villaraigosa_n_1262552.html