Democratic lawmakers, from the leadership on down, are facing what many describe as an unprecedented amount of political pressure as the party scrambles to pass health care reform.

In recent days, the message has been conveyed throughout the caucus that the failure to pass legislation into law would be a cataclysmic misstep. It goes beyond the certainty that activists in the base would be demoralized, that the president would be weakened or that Congress would seem entirely ineffectual (if not so already). The damage to the party would be so far-reaching, lawmakers have been told, that even the big-time donors who have long supported Democratic causes would be less inclined to contribute.

"The party is on a precipice," said one longtime Democratic donor who asked to speak on the condition of anonymity. "If they pass this [bill], people will be jubilant. If they don't, there are going to be a lot of us who consider just staying home in 2010."

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Messages like these aren't isolated. Party strategists say that members of Congress have been getting these warnings for weeks. Coupled with rising angst among the party base and a mounting hysteria among the activist community, the result is a merging of Democratic forces usually witnessed only during presidential campaigns.

"I have, in the last week, seen folks in the grassroots and the netroots and the donor community threatening to [stop supporting Democrats] if they don't get this done," said Paul Begala, a longtime Democratic strategist who consults many party officials. "You rarely get all three of them together on the same page."