WASHINGTON -- Immigration reform hit its first speed bump Monday when conservative talk radio kingpin Rush Limbaugh came out against a new bipartisan proposal.

As five U.S. senators appeared on Capitol Hill to talk about their agreement, Limbaugh -- whose daily show has one of the largest weekday audiences -- made his first on-air comments about their plan.

"We've done this before. We've done amnesty before," said Limbaugh. "This immigration bill that everybody's touting on TV today is essentially the Bush immigration bill that was beat back in 2007."

Limbaugh announced that Sen. Marco Rubio (R-Fla), one of the eight senators driving the new proposal, will be interviewed on his show Tuesday.