U.S. Constitution Article 1 Section 8 Clause 15:
"The Congress shall have Power to provide for calling forth the Militia to execute the Laws of the Union, suppress Insurrections
"The United States shall guarantee to every State in this Union a Republican Form of Government,
My personal view of this particular issue is that Bush's bracero program was well-meant and sincere but probably still-born. I'm not against immigrants, I'm for them. But there are laws and controls about immigration that are very much within the rightful purview of the federal government, and it is unjust to expect immigrants from one country to respect them when immigrants from others are allowed to openly flout them.
People speak of "sealing the border" as if it were an easy thing to to - it isn't, and no one is going to snap his fingers and stop the flow of migrants. But clearly the effort expended at the current time is simply not up to the challenge.
Mind you, conservatives who do insist that the federal government do something about this are voting for a larger, more expensive, more pervasive government. That grates against a lot of conservative principles, and is justified only by a problem of considerable magnitude. The issue at hand is whether this problem has reached a magnitude that will justify more government. Clearly the consensus of people living in that area hints to me that it has.
It need not be all federal; indeed, state efforts in this regard should be strengthened - more local government is preferable, IMHO, to more federal government. Many in the federal government will fight that, some out of an elitist desire not to let locals subvert national policy for their own interest, and others out of the true conviction that it really is a federal issue when all is said and done. But that sort of internecine warfare does very little to address the problem.
There is also a partisan aspect to this that is a sad fact of modern politics. Republican strategists are reluctant to take courses of action that will alienate the Hispanic vote, especially now that it is trending their direction. Democrats are pushing for full voting rights for illegals out of the conviction that they will benefit from their numbers. Both of these positions are, in my view, short-sighted and sordid but they're an inescapable feature of practical politics.
So what's a thinking conservative to do? Petition the government insistently for one. Vote locally depending on the issue for another. Strengthen state and local efforts first. And let government at all levels know that inaction is no longer an option, and that the "vigilantes" are there for a pretty good reason.