Washington ? After a decade in the political wilderness, Democrats are beginning to predict confidently if quietly that they will win control of the House in next week’s elections, and possibly emerge with a relatively robust majority.

The optimism coincides with a Republican retreat Tuesday in three costly, highly competitive races in Pennsylvania, Colorado and Ohio, as well as polls showing continued public dissatisfaction with President Bush and the war in Iraq.

In addition, fundraising is running significantly stronger than two years ago, $104.5 million through Oct. 18. That represents an increase of more than 30 percent, and has allowed Democrats to launch late-campaign television advertising in several districts in recent days in an attempt to maximize their gains on Election Day.

Mark Mellman, a Democratic pollster, said in an interview there has never been an election in which a president’s approval rating was below 40 percent “and his party has not lost the 15 seats” that Democrats need to gain control this year. Bush’s approval ratings hover in the mid- to high 30s.

Despite the developments, Rep. Nancy Pelosi, the Democratic leader, and Rep. Rahm Emanuel, the head of the campaign committee, have told aides to avoid predictions of victory before the votes are counted.

“Anybody who’s been involved in politics for the past 10 years can tell you that a week out you’ve still got a long week ahead of you,” said Bill Burton of the Democratic campaign committee. “And we are absolutely not taking anything for granted.”

Republicans, too, say that with a week of campaigning to go, Democrats are ill-advised to celebrate. They note than an extraordinary number of races remain very close, and that their GOP get-out-the-vote operation will help pull enough of their candidates to victory to preserve their majority.

Mellman said academic models predict Democratic gains of between 14 and 32 seats. Steve Elmendorf, a Democratic lobbyist, said a majority of 15 to 20 seats is possible, indicating gains of 20 to 35 seats on Election Day. Others predicted gains in the same range.

One of the most reliable indicators of competitive seats is party-financed television commercials or other political activity designed to augment a candidate’s effort.

By that standard, more than 50 Republican-held seats are competitive, and Democrats have made six-figure investments in television advertisements in many of them. Republicans have done likewise.

Republicans pulled back in three such races during the day, including Rep. Curt Weldon’s re-election bid in Pennsylvania and open seats held by Rep. Bob Beauprez, running for governor of Colorado, and Bob Ney of Ohio, who recently pleaded guilty to corruption charges.

In recent days, Democrats have moved into districts long viewed as untouchable. They launched advertisements in a western district in Nebraska; for an Idaho seat; and as a challenge to Rep. Jim Ryun in Republican-heavy Kansas. Nancy Boyda is running against Ryun.