A day after House Democratic leaders cut a deal with Blue Dog Democrats, there were even more public headaches for Speaker Nancy Pelosi, as dozens of more liberal lawmakers publicly threatened to vote against a health care bill unless changes sought by moderates are reversed.

"We expect the bill will retain a robust public option," said Rep. Lynn Woolsey (D-CA).

"If it doesn't, we will vote against it," said Woolsey who waved around a letter for House leaders, which by late on Thursday had almost five dozen signatures on it from House liberals.

With those kind of numbers, they could bring down the health care bill, just like the 52 Blue Dogs could - if they really wanted to.  For now, it's just a threat.

Still, such talk was greeted with loud cheers at a news conference outside the Capitol, where demonstrators were at the same time urging action on a Single Payer health care system.

Woolsey and others argue changes agreed to with the Blue Dogs would water down the public option to the point of making it useless, all in the name of saving money.

"We must continue to reject these claims that the cost of reforming health care in America is something that our nation cannot afford," said Rep. Barbara Lee (D-CA).

"Health care should not be a privilege," Lee said to more cheers.

While the liberals demanded a "robust" public option, Speaker Pelosi was vowing to support a "strong" public option in a news conference, where she tried to downplay the differences between Blue Dogs and Liberals, saying there was no major split.

"I don't see it that way, I don't see it as different wings.  We're all part of the same party," said the Speaker, who several times said the deal with the Blue Dogs provided a big boost to health care efforts.

"We will have a bill that will come to the floor, and when it does, it will pass," Pelosi said at a news conference.

Two weeks ago, that seemed like a possibility, but with all the troubles in the U.S. Senate on health care reform, getting a floor vote in the House will not be easy.