House Speaker Nancy Pelosi says Democrats are voting on the historic health care overhaul as a gesture for the American people.
But as Pelosi emerged from the final caucus meeting before the historic vote, protesters chanted her name and shouted to "kill the bill."
Pelosi led her caucus across the street to the Capitol with a gavel in one hand and the other on the arm of Rep. John Lewis of Georgia, who had been harassed by protesters on Saturday.
Even as they headed into the heated atmosphere of the House chamber, Democrats were scrambling to line up the last of 216 votes required to pass the bill. Some of the holdouts remained concerned that the legislation would permit federal money to be use for elective abortions.