WASHINGTON -- New Mexico Gov. Susana Martinez (R), whose named has been floated as a possible Republican vice presidential pick, slammed Mitt Romney on Monday for his immigration strategy.

Martinez took aim at Romney's support for a policy of "self-deportation," whereby conditions in the U.S. would be made so uncomfortable for undocumented immigrants that they would voluntarily leave the country.

"Self-deport? What the heck does that mean?" Martinez said in a Monday interview with Newsweek. "I have no doubt Hispanics have been alienated during this campaign. But now there's an opportunity for Gov. Romney to have a sincere conversation about what we can do and why."

Martinez also called on Republicans to step up their support for comprehensive immigration reform, in part to highlight that President Barack Obama hasn't been able to advance the issue, despite making a 2008 campaign promise to do so.

"I absolutely advocate for comprehensive immigration reform," Martinez said. "Republicans want to be tough and say, 'Illegals, you’re gone.' But the answer is a lot more complex than that."

The New Mexico governor specifically called for an immigration reform plan that includes increased border security, deportation for criminals, a guest-worker program for people to go freely back and forth across the border for work, and a DREAM Act-type pathway to citizenship through the military or college.

Most notably, however, Martinez endorsed the idea of providing visas to millions of undocumented immigrants living in the country, as long as they pay a penalty and agree to follow standard nationalization procedures.

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