UPDATE: During an interview on The Ed Morrissey Show, Rubio said he would not support any legislation that does not guarantee enforcement and border security before the Green Card process starts.

“We have to make sure this law is structured in a way that guarantees enforcement,” Rubio said, adding if we don’t do both, enforcement and citizenship, we’ll see another wave of undocumented people in the future.

Legislation is expected in March and possibly introduced to the Senate floor in April.

A bipartisan group of Republicans and Democrats have just wrapped up a press conference revealing what they are calling the “principles” of an immigration reform plan. The plan will serve as an outline for lawmakers to use when drafting legislation, which is expected to be introduced as early as April 2013. The key to the legislation and the bipartisan nature of the plan is the promise of border security and enforcement in return for a pathway to citizenship.