As Senate Democrats prepare for the midterm elections of 2006 after a series of bruising losses this year, many are taking their cues from the New York senator, who has been tapped by Democratic leaders to try to engineer the party's Senate comeback. Mr. Schumer has buttonholed his colleagues over the last six weeks, trying to bring himself up to speed on the home-state political realities each of them faces and offering them advice. And he plans to get together with all of them at some point at the beginning of the year, when Congress returns to convene a new session, his aides say.

On the surface, Mr. Schumer might seem an unlikely choice to take a lead role in a national Democratic campaign: a Northeastern Democrat in a nation that gave Republicans a firm grip on Washington with victories in one state after another in the November elections.

But Democrats say that anyone skeptical about Mr. Schumer's qualifications need only to look at his record in New York, where he has combined a talent for publicity with an eye for issues that have bipartisan appeal and a reputation for exhaustive constituent service. He won re-election with a record 71 percent of the vote in November, including one-third of the Republican vote, much of it in rural and old industrial regions that independent political experts say resemble Midwest swing states like Ohio and Michigan.

Even Republicans say that while it may be tempting to caricature the senator as the sort of Democrat that voters seemed to reject in November - a liberal-leaning Northeasterner - it would be dangerous to underestimate Mr. Schumer, a man so seemingly driven that he met a challenge from a magazine reporter to draw all 62 New York counties freehand.

"You can't outwork him," said Representative Thomas M. Reynolds of western New York, who is the chairman of the Republican Party's re-election committee in the House.

In his mission to revive Democratic prospects in the Senate, he faces the immediate task of helping defend five Democratic senators in states that President Bush carried or did surprisingly well in, analysts say. They are Senator Ben Nelson of Nebraska, Mr. Dayton of Minnesota, Kent Conrad of North Dakota, Jeff Bingaman of New Mexico and Bill Nelson of Florida. One of them, Mr. Dayton, said Mr. Schumer gave him one valuable piece of advice over dinner: hold regular news conferences on Sunday, a ploy Mr. Schumer has long used to avoid competing with major news for the press's attention.

In New York, Mr. Schumer's Sunday pressers, as they are called, have become such a fixture in local politics that his opponent in this year's election, Howard Mills, held his own "presser" to announce that he would "plant 25 trees to replace the trees killed last year to print Chuck Schumer's press releases."

But even though Mr. Schumer is sometimes mocked for his press events, Mr. Dayton is high on Mr. Schumer's suggestion. "I'm trying to prey on the Minnesota press in the same way," Mr. Dayton said in an interview. "I've gained press that I could not have without his advice."

Mr. Schumer brings another asset to the table that his fellow Democrats hunger after: direct access to a wealthy network of campaign contributors, many of whom have companies based in New York and want to curry favor with politicians in the state.

Indeed, Mr. Schumer managed to raise a staggering $27,421,709 in the nearly six years he has been in office, largely by tapping well-heeled donors on Wall Street and in New York's securities and banking industry.

Political analysts in both parties agree that Mr. Schumer's immense war chest helped him ward off any major challenge from New York Republican leaders, who wound up fielding Mr. Mills, a little-known candidate, to mount token opposition to him.

Now Mr. Schumer has turned his attention to helping provide a similar financial edge to his Democratic colleagues, among them Mr. Nelson, a first-term senator in heavily Republican Nebraska.

Recently, for example, Mr. Schumer came up with the idea of getting a prominent Nebraskan now living in New York City to headline a fund-raiser for Mr. Nelson: Bob Kerrey, the New School University president and former senator, who spent months in the national spotlight as one of the more outspoken members of the commission investigating the 9/11 terrorist attacks.

"Early money speaks," Mr. Nelson said in an interview. "He's bringing that message to the rest of us who are running in '06."

But Mr. Schumer's new job has other demands. He recently pulled aside every Democratic senator who may be poised to retire at the end of 2006 and implored each to stay on for at least one more term.

He is hoping to avoid the electoral disaster of this November, when Republicans swept five Southern seats that had come open with a string of Democratic retirements. But Mr. Schumer would not say how many of the senators took up his call.

As if that were not enough, Mr. Schumer may have a problem back home in New York. Hillary Rodham Clinton, the state's junior senator, is up for re-election in 2006. People close to her are arguing that she should skip her re-election campaign and instead focus her energies on a race for the White House in 2008. But Mrs. Clinton's aides say she intends to run for re-election in 2006.

Then there is another potential headache for Mr. Schumer across the Hudson River in New Jersey, where Senator Jon S. Corzine is also up for re-election in 2006.

The problem is that Mr. Corzine has decided to run for governor next year. That means a newcomer will have to be found to fill his Senate seat if Mr. Corzine wins the governor's race. "The task is tough, but I am optimistic we can succeed," Mr. Schumer said recently.

But perhaps Mr. Schumer's biggest challenge is an electoral map of the nation that seems to be shifting Republican.

Mr. Schumer has reached out to Ms. Cantwell, the first-term senator from Washington State who won in 2000 in the tightest Senate election in the country that year.

Mr. Schumer urged her to drop in on every major media market in the state at least once a month to get as much free news coverage as possible between now and November 2006, according to aides to both senators.

Ms. Cantwell, who knows Mr. Schumer from their days in the House, has taken the advice. Such retail politicking, she said of Mr. Schumer, is "instinctive with him."