WASHINGTON — Senator Clinton and her Democratic presidential rivals are targeting the labor vote here, as Mrs. Clinton yesterday assailed a corporate boardroom culture that she said does not understand the plight of American union workers.

In a campaign speech, she told members of the Communications Workers of America that executives have “disregarded wholesale” the nation’s balance of power, saying corporate profits and CEO salaries are rising while wages for the average employee are stagnant.

“There is a mood in unfortunately too many corporate boardrooms that we don’t have to take care of the people who take care of us — we don’t have to do our duty to America,” she said. “That’s what this is at bottom about.”

Mrs. Clinton cited the contribution of unionized workers in the aftermath of the September 11, 2001, terrorist attacks, saying they helped reconnect Lower Manhattan after cell phone service and other communications were interrupted.

Criticizing the Bush administration, the former first lady later drew applause when she pledged to appoint officials to the Department of Labor and the National Labor Relations Board who are “actually pro-labor.”

Mrs. Clinton followed Senator Obama of Illinois and a former North Carolina senator, John Edwards, in addressing the CWA’s political conference. All three leading Democratic contenders also plan to speak today at a presidential forum sponsored by the Building and Construction Trades union, an affiliate of the AFL-CIO.

The labor events coincide with the busiest fund-raising week of the campaign, as candidates are scrambling for contributions from top donors before the first quarter filing deadline on March 31, considered an early benchmark for White House hopefuls.

Union members greeted all three contenders with loud applause, and they gave an extended ovation to Mr. Edwards, who has dominated the news following the disclosure last week that his wife, Elizabeth, is battling an incurable recurrence of cancer.

Mr. Edwards thanked the crowd and briefly touched on his decision to continue his campaign despite his wife’s illness, placing it in the context of a campaign theme of “two Americas” that he developed when he first sought the presidency, in 2004. “People want to know why I continue this campaign for president, why both Elizabeth and myself are so committed to this cause, to this crusade,” Mr. Edwards said. “Because I want everybody in this country to have the same chances that I’ve had. I came from a place of having nothing to having everything. And in today’s America it is so hard for people to work themselves up.”

The former vice presidential nominee gave a labor-oriented stump speech, calling for passage of the Employee Free Choice Act, which supporters say would make it easier for employees to join unions. He also touted his plan for universal health care and urged expansion of Internet access to rural areas and a crackdown on predatory lenders.

Earlier, Mr. Obama accused the Bush administration of “social Darwinism” in ignoring the gap between the rich and poor. “It’s a strategy that we’ve seen this administration pursue over the last six years, that basically says government has no role to play in making sure that America is prosperous for all people and not just some,” Mr. Obama said, according to the Associated Press.

After the speeches, several audience members said they came away most impressed with Mr. Edwards, citing the specifics of his pro-labor message. “I just like Edwards. He has detailed plans,” a Washington-based economist for the union, Ken Peres, said. “They’re at a good level speaking about issues,” he said of Mrs. Clinton and Mr. Obama, “but I want more meat. I want more beef.”

Mrs. Clinton’s critique of boardroom culture drew criticism from the National Association of Manufacturers, which defended employer practices. “We would take issue and disagree, respectfully, with her comments,” a policy director for the group, Jason Staczewski, said.

A labor policy analyst at the conservative Heritage Foundation, James Sherk, disputed the contention by Mrs. Clinton and other Democrats that conditions for union workers had deteriorated in recent years, saying the standard of living for the middle class has risen. “It’s rhetoric designed to get support from an interest group that has contributed generously to her,” Mr. Sherk said of Mrs. Clinton’s comments. “It’s not so grounded in fact.”