IMPEACH BUSH

WASHINGTON -- Republicans are bracing for double-digit losses in the House and the prospect of four or five losses in the Senate, as they fight to hold a wide range of districts and states normally seen as safe for them, from Alaska and Colorado to Mississippi and North Carolina.

The feared setback for Republicans, coming two years after their 2006 drubbing, is unusual for several reasons. It is rare for a party to lose two election cycles in a row. And many expect losses even if their presidential candidate, John McCain, captures the White House.

Democrats already hold majorities in the Senate and House. Democrats hold 49 seats in the Senate, and they often have the votes of the chamber's two independents. In the House, Democrats have 235 seats compared with 199 for Republicans.

But a wider margin of control in both chambers would give the party a more workable majority, a change that would let it push more ambitious agendas on health care, energy policy and tax issues. While Democrats are already able to pass much of their agenda through the House, many of those bills currently get stuck in the Senate. A handful more seats in that chamber would give Democrats a better chance of overcoming filibusters, which require 60 votes to break.

"A lot of Republicans thought that 2006 was the low point, and that simply isn't the case," said Nathan Gonzales, political editor of the nonpartisan Rothenberg Political Report, which predicts Democratic gains of eight to 12 seats in the House and three to five seats in the Senate.

"It's like 2006 never ended for Republicans," said Jennifer Duffy, of the nonpartisan Cook Political Report, which predicts Democratic gains of 10 to 20 seats in the House and four to seven in the Senate.

Already this year, Republicans have lost three House seats in special elections in Republican-leaning districts, an alarm bell for many in the party as they strategize for campaign season.

The dynamics at work: voters' sharply negative views of President Bush and dismal feelings about the direction of the country, including rising oil and gas prices, a weak economy and fallout from the housing crisis. Even though Congress continues to register low approval ratings, voters overall appear to prefer putting Democrats in charge.

Much remains fluid in the five months that remain until Election Day, and the presidential contest between Barack Obama and Sen. McCain might sway the outcomes of House and Senate races. Republicans are hoping Sen. McCain will aid their appeal to independents and the white, working-class voters who remain leery of Sen. Obama. Sen. McCain also will deflect attention from Mr. Bush.

"McCain being at the top of the ticket improves the bad atmosphere, I think," said Rep. Jim McCrery, a Louisiana Republican who is retiring from Congress. "I don't think the atmosphere in November is going to be nearly as bad as it is now, or as pundits suggest."

But, many Republicans say privately that, barring a huge gaffe by Sen. Obama, they have little hope of holding their current numbers, much less gaining ground. Sen. John Ensign of Nevada, who is heading Senate Republicans' re-election effort, recently told the Las Vegas Review-Journal that it would be "a great night" if his party can hold Democratic pickups in the Senate to three or four seats in November.

In both houses, Democrats also have a financial advantage. At the end of April, House Democrats' campaign arm had $45.3 million in cash on hand compared with $6.7 million for Republicans. That lets Democrats spend money on a broader swath of races and defend freshman House members whom Republicans view as most vulnerable.

The Senate Democrats' campaign arm had $37.6 million in cash compared with $19.4 million for Republicans.

David Wasserman, who analyzes House races for the Cook Political Report, said Sen. Obama's appeal among upper-income white voters is expected to help Democratic House candidates in suburban districts, such as those held by Republican Reps. Mark Kirk of Illinois and Dave Reichert of Washington.

Black turnout in states such as Virginia and Ohio could also help Democrats beat Republican House members. Reps. Steve Chabot of Ohio and Thelma Drake of Virginia, both Republicans, are facing more competitive races in part because their districts have high percentages of black residents who are likely to support Sen. Obama.

New York and New Jersey Republicans face a tough environment. Sen. Obama is expected to win those states, likely boosting the prospects of Democrats vying for seats left open by retirements, such as those of Reps. Jim Walsh and Tom Reynolds.

In Alaska, usually one of the most reliable Republican states, the party is in danger of losing both a House seat and a Senate seat. In an echo of the scandals that damaged Republicans two years ago, both Sen. Ted Stevens and Rep. Don Young are under the cloud of a federal corruption investigation; they deny wrongdoing.

Beyond the political dynamics, Senate Republicans have the handicap of far more seats to defend than Democrats do, because they won far more seats in 2002, when the climate was more favorable to the party. And they have more incumbents retiring.

"There are 23 states that we're defending compared to their 12," said Rebecca Fisher, a spokeswoman for the National Republican Senatorial Committee. "We're in a defensive crouch."

The toughest Senate race for Republicans is in Virginia, where popular former Gov. Mark Warner, a Democrat, is running for the open seat left by retiring Republican Sen. John Warner. Also challenging are highly competitive races in New Hampshire and New Mexico, another open seat.

Republicans are seen having just one Senate opportunity to pick up a seat -- the one held by Democratic Sen. Mary Landrieu in Louisiana, which has trended more Republican after Hurricane Katrina displaced many of the state's residents.

Write to Sarah Lueck at sarah.lueck@wsj.com