Sen. Marco RubioMarco RubioGlenn Beck: I was wrong about Ted Cruz Senate rivals gear up for debates Rubio: End of Obama's term could be 'most damaging yet' MORE (R-Fla.) warned President Obama on Tuesday that sweeping executive action on immigration would preclude any meaningful reform from Congress.
"If indeed you move forward on such a decision, I believe it will close the door to any chance of making progress on immigration reform for the foreseeable future," Rubio wrote in a letter sent to Obama on Tuesday.
Rubio, a potential 2016 presidential candidate, said there is no realistic path for a comprehensive immigration deal in Congress. But he continued to advocate for a piecemeal approach. Stanching the flow of illegal immigration and fixing the legal immigration system would have to happen before Congress deals with the millions of people already here illegally, he said.
Rubio said even a step-by-step approach would be impossible, however, if Obama acts on his own. He pointed to the backlash from Republicans in 2012, after the Department of Homeland Security changed federal deportation policy under Deferred Action for Childhood Arrivals, which de-prioritized many young illegal immigrants for deportation.
"They argued that no matter what we wrote into law on enforcement, your administration would simply ignore it," Rubio said.
He added: "Furthermore, your pursuit of unilateral action in the midst of an election year, without any concern for the policy ramifications, has played a significant role in the humanitarian and security crisis that has been occurring on our border with Mexico."
President Obama has tasked his administration with outlining executive steps he can take on immigration. He will decide by the end of the summer.
Rubio was a key Republican supporter of the comprehensive Senate bill passed last year, which would have granted a path to citizenship for the millions living in the country illegally. He was heckled by a number of immigration advocates on Monday in South Carolina for giving up on the deal.
Rubio, in his letter, said the Senate bill last year helped lead "to the stalemate we now face on this issue."
The Florida Republican said Obama inherited a broken immigration system, but it has been turned into "unsettling chaos" under his tenure.
"I know you are receiving tremendous political pressure from certain activists to grant another unilateral, temporary and uncertain legal status to millions of additional undocumented immigrants," Rubio said.
But he warned it would set back real reform and incentivize people to immigrate to the United States illegally.