Nelson: Border security trigger inevitable in immigration deal

"Guest workers, agricultural workers have to be included. Border security, in order to get the votes in Congress, is going to have to be included, and the question is, what is the trigger?" Nelson told CNN. "That is to be worked out; that is reasonable; that is going to be worked out."

White House officials have said they object to any effort to tie a path to citizenship to border security goals, saying that while they support increased patrolling, they are wary of a proposal that could leave the nation's 11 million illegal immigrants in limbo.

"For comprehensive immigration reform to work, it must be clear from the outset that there is a pathway to citizenship," Obama said on Tuesday.

But Republicans have said pairing the two is a necessary part of any immigration deal, and Nelson seemed to acknowledge that it was necessary to move the bill through Congress.

On Monday, Sen. John McCain (R-Ariz.) said increased border security must be addressed before "we move on with [immigration]."

"We have to use a lot of high-tech — we’ve got to use drones, we’ve got to do a lot of things to get that border secure, but that must be done," McCain said.

On Tuesday, Sen. Marco Rubio (R-Fla.) said the president had "an important decision to make" about whether to embrace the Senate plan, which would make the opportunity for citizenship contingent on increased border security.

"He can either decide that he wants to be part of the solution, or he can decide he wants to be part of a political issue and try to trigger a bidding war. I'm not going to be part of a bidding war to see who can come up with the most lenient path forward," Rubio told Rush Limbaugh.

Asked about Rubio's comments, Nelson said that his fellow Florida senator had to use strong language to give "cover to a lot of the Republicans that had taken the opposite position."

"Just wait till you get the details," Nelson said. "They'll hammer it out."