On a straight "generic" ballot, 46 percent of voters said they'd vote for the Democrat if the election for Congress were held today, 38 percent support the Republican and 16 percent are undecided, according to the poll conducted Nov. 13-15.

If Congress fails to pass a health care bill, that Democratic advantage evaporates, leaving the two parties tied at 40 percent each with 20 percent undecided. If the bill passes with a government-sponsored "public option" to compete with private insurers, the Democrats lead 46 percent to 41 percent with 14 percent undecided.

But the concern for Democrats is how independent voters, who polls indicate are getting antsy about President Obama and the Democrats, see these outcomes. Independents break 37 percent to 30 percent for the Democrats with 33 percent undecided on the overall generic ballot, but that number drops to a 31 percent tie with the passage of the health care bill, with 38 percent undecided. And, if a health care bill passes with the public option, independents turn against the Democrats by a 44 percent to 37 percent margin with 20 percent undecided.

"The political damage for Democrats of passing a public option is not as bad as the damage from doing nothing," said PPP. "But they would still be better off passing something that's not perfect than passing nothing at all. Most voters aren't following this debate really closely and don't understand the nuances of it all. At the end of the day voters are likely to see this as either a bill was passed or it was not. . . . Democrats would still be better off, at least for next year's election, with a weaker bill than no bill at all."

PPP's 46 percent to 38 percent margin for Democrats on the generic ballot differs from what Gallup found in its poll conducted Nov. 5-8, which had Republicans ahead by 48 percent to 44 percent. PPP is a Democratic-affiliated pollster.

Another poll released today -- this one by Rasmussen Reports -- said that public support for the health care reform proposals pushed by Obama and the Democrats has fallen to 38 percent, the lowest level since June. Fifty-six percent oppose the proposals, with 43 percent of those "strongly" opposing them and 6 percent are undecided.

Other measures of public sentiment in the poll also were more negative.

Fifty-four percent believe that the quality of health care will get worse under reform legislation, 20 percent say it will get better, 19 percent predict it will stay the same and 6 percent are undecided.

Sixty percent say costs will go up if the legislation passes, 18 percent say they will stay the same, 16 percent believe they will go down and 6 percent are undecided.

The poll was conducted Nov. 21-22.