Andrew Kohut, a pollster who is the director of the Pew Research Center, said the public was as unhappy with Congress as at any time in the history of the Pew Poll, and that a third of those polled in his most recent survey said they would use their congressional vote as an opportunity to vote against Bush, which is precisely the way Democrats have been trying to frame this election.

"Everything is pointing to a pretty big Democratic victory if attitudes toward Congress remain as negative as they are and attitudes toward President Bush remain as negative as they are," Kohut said. "It's hard to imagine any way that wouldn't happen."

Some analysts emphasize that it remains early in the season, that the field of vulnerable Republican seats remains relatively small, and — perhaps most significant — that Republicans will have a big spending advantage over Democrats by fall.

The Republican National Committee collected $17 million at a Washington fund-raiser last week. The party chairman, Ken Mehlman, said in an interview that most of that money would go to help embattled Republican congressional candidates, a show of financial force that could frustrate Democrats in their search to win control.

Howard Dean, the Democratic Party chairman, has instead sent money he has raised to state parties for party-building, over the objections of congressional leaders.

Rep. Thomas M. Reynolds, the chairman of the Republican Congressional Campaign Committee, said he was confident that his party would maintain control of the House, and pointed to Democrats who are vulnerable in Georgia and Illinois.

"If you think I'm sitting here on defense — never going to happen," Reynolds said in an interview. "We are on offense on both open seats and challenged seats, while we do everything we can to protect our incumbents. I am ready for a race."

Reynolds said talk of an expanding map was unfounded and was being orchestrated by his Democratic counterpart, Rep. Rahm Emanuel of Illinois.

"He is trying to convince himself first, his Democratic conference second and the downtown pundits and financial supporters that he has more seats in play," Reynolds said. "I don't see any more than I have before."

Other Republicans were less sanguine.

"Right now, there is no doubt that Democrats have the advantage. I see a disenchantment with Republicans," said Rep. Peter T. King, R-N.Y. "We are losing it, but Democrats aren't really winning it. We can turn it around by November."

One senior Republican strategist, granted anonymity because his assessment would put him at odds with party leaders, said that Democrats were succeeding in their main goal: turning the race into a national referendum on Bush and the Republican Party. "Is the race being nationalized?" this strategist said. "Yes."