Florida Sen. Marco Rubio (R) spoke with Your World host Neil Cavuto Thursday, reacting to criticism of the "Gang of Eight's" immigration plan. Rubio blasted failures of the Obama administration that he says are making it 'challenging' when it comes to formulating legislation.

"The fundamental challenge we have here is that no one believes the administration is serious about enforcing [immigration] laws," he said. "So, we need to figure out a way to guarantee - in the law - that [...]  the border will be secure."

Of the current bill, Rubio said it serves as the "starting point" for discussion, and he encouraged any colleagues with an 'idea on how to do it' to let him hear it.

Rubio also weighed in on any possible impact last week's Boston bombing attacks will have on immigration law.

"If it exposes flaws in our system, then we should address that," he said, adding that the national security checks required in the current bill should potentially be expanded to others who are here legally but could pose a threat.