SHARON, Pa. — Just up the hill from a huge, shuttered Westinghouse factory, three campaign foot soldiers from the United Steelworkers rang Ed Turosky’s doorbell to urge him to vote for the Democratic candidates for the House and Senate here.

It was a beautiful autumn morning, but Turosky, a retired steelworker himself, greeted them with surprising gruffness. He said he wasn’t buying what they were selling; in fact, he wasn’t going to vote at all, even though he is a lifelong Democrat.

"I’m mad at all of them; they’re all crooks," he said, angry that the government is not increasing his monthly Social Security payments for the second year in a row. "I have no use for any of them."

This fall, the Democrats are looking far more than usual to organized labor’s ground troops and financial resources to save embattled Democratic candidates. But labor’s vaunted political clout may fail to deliver — partly because so many union members and retirees, like Turosky, are angry about the economy, and partly because unions are finding it hard to surmount the deluge of Republican campaign advertisements.

In recent days, several unions have not just poured a record number of canvassers into the streets going door to door, but they have promised record amounts of campaign spending in a last-ditch effort to counter corporate spending and limit Republican gains in House, Senate and gubernatorial races.

"It’s been more difficult this year," said Rick Bloomingdale, president of the Pennsylvania AFL-CIO. "We don’t have the resources to keep up. We’re being deluged by the Chamber of Commerce and all these AstroTurf groups that pretend to be friends of the worker," a reference to fake grass-roots organizations.

Like the Democratic Party, labor unions see some Democratic candidates so far behind that they have written them off. But, Bloomingdale said, "There are races where if it’s close, we can make the difference. If we can get it within 5 points, we can make the difference. If the gap is 20 percent, there’s not much we can do."

The giant union of government employees, the American Federation of State, County and Municipal Employees is promising to spend a record $66 million this year on get-out-the-vote efforts, voter education and political advertisements. That includes $16 million that the union recently took out of an emergency fund, and it comes on top of $21 million it spent last year, mainly on state and local races. The union says it has spent $17 million on broadcast advertisements so far this year.

Reflecting a growing dispute between unions and the Chamber of Commerce, the public employees union is arguing that its campaign spending this year is less than the Chamber’s $75 million, even though the union has spent $87 million over the two-year election cycle.

The AFL-CIO plans to spend about $50 million in this year’s campaign, while the Service Employees International Union, one of the most politically active unions, plans to spend $44 million, including $14 million already spent on advertisements.

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Labor’s role is especially important to the Democrats because it succeeded in 2008 in making inroads with a crucial demographic: blue-collar white males. While white male nonunion workers voted against President Barack Obama by a margin of 16 percentage points in 2008; he won among white male union workers by 18 percentage points. Moreover, these voters are in the swing states that matter. For instance, about 30 percent of Pennsylvania voters come from union households, as do 35 percent of Ohio voters.

Both states have hard-fought, crucial races for governor and U.S. senator.

AFL-CIO leaders say that of the 75 Democratic House seats in play, 37 of those districts have high union membership, with more than 40,000 union voters.

The AFL-CIO says that so far this fall its volunteers have given out 17.5 million leaflets, made 23.6 million phone calls, mailed out 18.6 million flyers and knocked on 1.3 million doors.

Here in Pennsylvania’s Third Congressional District, an area of stunning fall foliage and rusting factory carcasses, Andy Harkulich, president of United Steelworkers Local 1660, voiced confidence that labor can save Rep. Kathy Dahlkemper, a first-time Democrat — helped by the 64,500 voters from union households who live in the district. Labor is pushing especially hard across Pennsylvania because polls show that the seats of five Democratic House incumbents, including Dahlkemper’s, are in jeopardy.

When she was elected in 2008, Dahlkemper became the first Democrat to represent the area in 25 years. Since then she has won labor’s heart, supporting stimulus spending, the health care overhaul and a tougher stance toward China on trade. Indeed, the tens of thousands of union leaflets distributed on her behalf hail her for "fighting for working families."

Last Saturday, labor volunteers knocked on several thousand doors in Dahlkemper’s district. Many homeowners thanked the union volunteers for plying them with information about her and other Democratic candidates. Dahlkemper’s Republican challenger, Mike Kelly, is a likable, former Notre Dame football player who owns a Cadillac, Kia and Hyundai dealership.

"I don’t think she can win without labor’s help," said G. Terry Madonna, director of the Center for Politics and Public Affairs at Franklin and Marshall College in Lancaster, Pa. "Labor has to pull out all the stops. I think they’re trying to, but it’s unclear whether that will be enough."

Kelly’s spokesman, Brad Moore, largely dismissed the impact of labor’s ground game, saying his candidate had a double-digit lead.

"There’s a lot of enthusiasm behind Mike’s candidacy and the Republicans this year," Moore said. "And just because union leaders have endorsed someone, that doesn’t mean the membership has the same feeling."

Political experts say labor’s recent push across Pennsylvania has played a significant role in lifting Joe Sestak, the Democratic candidate for Senate, in recent polls in his race against Pat Toomey, the Republican candidate.

Toomey’s campaign criticized labor’s role.

"They support Sestak because he has the same policies they have, because he supports empowering union bosses at the expense of workers," said Nachama Soloveichik, Toomey’s spokeswoman.

"There are a lot of groups that overshadow labor," she added. "Most of these are the groups on television."

For labor’s foot soldiers, a big change from previous years comes when they knock on doors to promote Dahlkemper or other Democratic candidates, homeowners often bristle because they have seen so many broadcast spots attacking that candidate, for instance, for backing the $787 billion stimulus plan when the nation already had a huge budget deficit.

Despite labor’s broadcast expenditures, union leaders say their main strength is on the ground.

"We can’t outspend the companies," said Harkulich, who oversaw a canvass by two dozen union volunteers last Saturday. "That’s why we have to beat our feet on the pavement. That’s how we compete against money."

Some homeowners nearly embrace the union visitors. Donna Carpec, a retired Packard Electric worker, welcomed their pro-Democratic message.

"I’m tired of listening to all that Republican garbage on TV," she said, praising Dahlkemper for backing the health care overhaul.

But Marie Borawski, a retired school secretary, was not that receptive, even though she voted for Obama in 2008.

"Everything is so rotten nowadays," said Borawski, the wife of a union retiree. "I feel so undecided. I might not vote this year."