The Senate health bill is drifting toward ending up with an "opt-in" provision versus an "opt-out," one Democratic senator said Friday.

Sen. Sheldon Whitehouse (D-R.I.) predicted that healthcare reform in the upper chamber would shift from its current construction, which allows states to opt out of a public option, to a version that forces states to opt into such a plan.

"I think it's falling into an opt-in, versus opt-out," Whitehouse said during an appearance on MSNBC. "You have a public option, but it's up to a state to take an affirmative act to take advantage of it."

Whitehouse suggested the opt-in as a potential compromise on the public option to win enough Democratic votes in the Senate, where Sen. Joe Lieberman (I-Conn.) has said he will vote against a bill containing a public option, and several other centrist Democrats have been reluctant to support the current proposal.

The Rhode Island Democrat asserted that Majority Leader Harry Reid (D-Nev.) probably has enough votes to bring the bill to the floor, where a number of lawmakers will be allowed to attempt amendments to the legislation.

But Whitehouse also suggested that the process would be drawn out, extending well into December and before the holiday recess.

"I'm betting on doing my Christmas shopping on the internet," he said.