Senate Minority Leader Mitch McConnell (R-Ky.) set the stage for a tough debate over the Senate immigration bill, saying Tuesday that the legislation has "serious flaws" and that Congress may very well fail to pass it.

"At the risk of stating the obvious, this bill has serious flaws," McConnell said on the Senate floor. "I’ll vote to debate it and for the opportunity to amend it, but in the days ahead there will need to be major changes to this bill if it’s going to become law. These include, but are not limited to, the areas of border security, government benefits, and taxes."

McConnell also alluded to the costs of creating a path to citizenship, saying it must be part of the equation.

“Some have also criticized this bill for its cost to taxpayers; it’s a fair critique," he said. "Those who were here illegally shouldn’t have their unlawful status rewarded with benefits and tax credits."

Senators will vote Tuesday afternoon on whether to proceed with a debate on the bill. McConnell said he will support that motion -- some Republicans are opposed -- which should pass easily.

“We tried to do something six years ago, and didn’t succeed. We may not succeed this time either," McConnell said. "But attempting to solve tough problems in a serious and deliberate manner is precisely what the Senate, at its best, should do. And it’s what we’re going to try to do in this debate.”