WASHINGTON >> Desperate Democrats are scrambling to save suddenly vulnerable House incumbents, even in states where President Barack Obama cruised to double-digit victories, amid fresh signs of Republican momentum less than a week before the midterm elections.

The once friendly terrain of New York, California, Obama’s native state of Hawaii and adopted state of Illinois all now pose stiff challenges to Democrats who are determined to limit their losses next Tuesday. Both parties agree that the GOP will hold its House majority; the question is whether Republicans can gain enough seats to rival their post-World War II high water mark of 246.

The current breakdown is 233-199 in favor of the Republicans with three vacancies.

In a clear sign of Democratic woes, Vice President Joe Biden was heading to Massachusetts on Wednesday for a rally with Seth Moulton, who is trying to hold onto a Democratic seat against Republican Richard Tisei. Then Biden was traveling to California on Saturday to campaign in an open-seat contest east of Los Angeles that surprisingly looks closer than a sure-fire Democratic gain.

“Heck, it’s been so long since a Republican was elected to the Congress in Massachusetts, most Republicans don’t know how to spell Massachusetts,” joked Rep. Greg Walden of Oregon, chairman of the National Republican Congressional Committee. He said the GOP is spending 78 percent of its independent money in districts that Obama won.

National Democrats are coordinating with local campaigns in Nevada, Hawaii and California in hopes of holding seats.

In one example, the Democratic Congressional Campaign Committee has bought $99,000 in radio ads for eight-term Rep. Lois Capps in her Santa Barbara-area race against Chris Mitchum, the son of the late actor Robert Mitchum. The GOP candidate has relatively little money still on hand for his campaign — $96,108 — but the contest is considered close.

The committee also reserved $360,000 in air time for ads for first-term Rep. Steven Horsford in his central Nevada district north of Las Vegas after the Karl Rove-founded group Crossroads GPS made a late ad buy of $935,000. And In Hawaii, the Democrats are spending $200,000 on television ads and voter outreach for Mark Takai, who is locked in a tight race with former Republican Rep. Charles Djou in an open Honolulu-based district that Obama won with 70 percent of the vote.

In the closing days, the Democratic committee has invested $1.1 million in an effort to protect six incumbents in Georgia, Illinois, Minnesota, West Virginia and California.

“We’re in trench warfare. I’m not going to sugarcoat it,” Rep. Steve Israel, D-N.Y., chairman of the committee, said in an interview. “It’s a tough climate, it’s getting tougher. It’s the worst climate for Democrats since 2010, but it won’t be 2010. We knew that this was coming and we prepared for it.”

The Democrats lost 63 House seats that year.

Any president’s party typically loses seats at the halfway point of his final term. This time the situation has gotten progressively worse for Democrats — and far better for Republicans — as Obama’s unpopularity has dragged down his party, GOP-leaning outside groups have spent freely and some independents have shifted to the Republicans.

“It’s a referendum year on the president and his policies,” said Walden, the GOP campaign committee chairman, in an interview. “We faced it in ’06, and I know how ugly it can be.”

With George W. Bush in the White House, the Republicans lost 30 seats in the House and six in the Senate in 2006, along with majority control of Congress.

Next week, 23 incumbent Democrats are in real jeopardy compared to just four Republicans as new races are added to the list of toss-ups. A greater House Republican majority would mean Speaker John Boehner of Ohio would be able to weather more defections on legislation and still get bills passed.

In Iowa, Republican Gov. Terry Branstad’s strength and Democratic Senate candidate Bruce Braley’s struggles are undercutting four-term Rep. Dave Loebsack and Democratic hopes of holding Braley’s open seat.

Three New York Democrats are endangered even though Gov. Andrew Cuomo is widely expected to capture another term. The same is true in California where Gov. Jerry Brown is an odds-on favorite to win again but four Democrats are considered vulnerable. Voters’ matter-of-fact attitude toward those two governors’ races has generated little energy for other candidates.

In all, the Democratic committee has outraised its GOP counterpart, but outside Republican groups have the edge over Democratic-leaning groups $49 million to $31 million since July 1. In a late money appeal, Democratic House leader Nancy Pelosi and Israel convinced Democratic incumbents and candidates to contribute some $500,000 and counting for the final days.

The party is relying on a big get-out-the-vote effort after registering 80,000 new voters in battleground districts.

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Illinois offers one of the tightest races along Chicago’s wealthy North Shore. First-term Democratic Rep. Brad Schneider is in a rematch with Republican Bob Dold, who won in the tea party wave of 2010 and lost in 2012.

Republicans are upbeat about reclaiming the seat as Democratic Gov. Pat Quinn struggles to win against Republican Bruce Rauner.

“It’s a unique opportunity the 10th district hasn’t seen in 30 years, comparing one term versus one term,” Dold said at the opening of a new upscale grocery. “This year, you’re talking about Pat Quinn at the top of the ticket versus President Obama, that’s a big difference.”

Miles away, Schneider toured a manufacturing business with Democratic Sen. Dick Durbin, who also faces re-election, and cast the election as a “choice between two very different visions.”

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Senate Majority Leader Harry Reid is reviving the “I” word — impeachment — in a fundraising appeal warning about GOP control of the Senate.

“Frankly, a Republican House and Senate could go beyond shutting down the government — they could waste months of our lives on impeachment,” Reid says in an appeal put out by the Progessive Change Campaign Committee.

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Associated Press writer Kerry Lester in Chicago contributed to this report.