Washington ? With President Bush’s political strength eroding, Democrats face improved electoral prospects this fall in the House and Senate — political terrain that not long ago seemed firmly in the GOP’s grip.

Recent polls indicate that problems in Iraq and continuing lack of confidence in the economy are not only hurting Bush, but undercutting voters’ assessment of Republicans in Congress.

The challenge for Democrats remains translating that general discontent into specific victories. But the party’s chances of winning control of the Senate have significantly improved in recent months — due to the unexpected strength of their candidates in several Bush strongholds and retirements by GOP incumbents. And the bid by the Democrats to take over the House, though still a long shot, would gain momentum next week if they win an open seat in South Dakota, a surprisingly likely prospect in a heavily Republican state. That would be the Democrats’ second victory in a special House election this year.

Republicans are clearly more edgy about the fight for Capitol Hill than they were a year ago. Back then, confident GOP leaders aspired to the ambitious goal of expanding their narrow control of the House and Senate to establish a durable majority that would dominate politics for years to come.

“The psychology has changed from one of (achieving) a permanent victory to maintaining the status quo,” said Michael Franc, a Republican who is a vice president of the Heritage Foundation think tank.

Not a threat … yet

Many Republicans also are heaving a collective sigh of relief that Election Day is not right around the corner.

“This is just the beginning of the summer,” said Rep. Zach Wamp, R-Tenn. “But if we get to Labor Day and we have these numbers in the polls, we have a big problem.”

In the House, where 218 seats constitute a majority, there currently are 228 Republicans, 205 Democrats, 1 independent who routinely votes with the Democrats and the one vacant seat. In the Senate, there are 51 Republicans, 48 Democrats and one independent who usually votes with the Democrats.

President Bush, flanked by Secretary of State Colin Powell, left, and Secretary of Defense Donald Rumsfeld, meets with his Cabinet in the White House in this Feb. 2 file photo. Missteps in Iraq and Bush's slumping approval ratings may be helping Democrats' chances to win more seats in Congress, polls show.

Even with those slender margins, many Democrats a year ago doubted they could capture either chamber.

In the House, new district lines drawn after the 2000 Census made safe seats even safer and reduced the potentially competitive ones to a few dozen. Then, with an eye on this year’s election, Texas legislators redrew House districts in the state to give Republicans the potential to gain up to six seats there.

In the Senate, the fight also began with a tilt against the Democrats because they had to defend 19 seats up for election, compared to the GOP’s 16. The outlook became grimmer as five Democratic senators from the South, a region Republicans have come to dominate , decided not to seek re-election.

Tide turning

But the recent breaks have gone to the Democrats.

Earlier this year, Republican Rep. Jack Quinn of New York announced he would retire, opening a House district that Democrats have a good shot at winning. A Democrat won a special election in Kentucky, taking over a GOP-held seat.

And in South Dakota’s June 1 special election, Democrat Stephanie Herseth has been leading Republican Larry Diedrich in the polls. The vote will fill the seat vacated after Republican Rep. Bill Janklow was convicted of manslaughter and reckless driving.

More broadly, Democrats are encouraged by recent polls showing their party has gained an edge over the GOP when people are asked how they would vote in congressional elections.

A Time/CNN poll found that 53 percent said they would vote for a Democratic candidate for Congress in their district, compared to 40 percent who said they would back the Republican. A survey for the Associated Press reported that that 50 percent wanted Democrats to win control of Congress, compared to 41 percent favoring the Republicans.

Andy Kohut, executive director of the Pew Research Center for People and the Press, said such results probably reflect weakening support for Bush rather than a solid indication of voting intentions. But they also are a reminder that “no president gets turned out of office without taking some of his brethren in Congress with him,” Kohut said.

Meanwhile, Democrats hope to score pickups in Colorado, Illinois and Oklahoma — seats opened up by GOP retirements. The Democratic candidate in Illinois is favored to win there, and the party has fielded strong contenders in the other two states.

Alaska, a GOP bastion, also has turned into a tight race. Republican Sen. Lisa Murkowski faces a primary challenge from the right and, if she survives that vote, tough Democratic opposition from Tony Knowles, a popular former governor.

“We are in an extremely volatile environment,” said Sen. Jon Corzine, D-N.J., chairman of the Democratic Senatorial Campaign Committee. “There has been a major failure to manage the occupation in Iraq, which opens up people’s minds to the question of whether there has been competent management on a bunch of other issues.”