Union leaders urged Vice President Joe Biden during a White House meeting last month to go to Wisconsin and rally the faithful in their fight against Gov. Scott Walker's move to curtail collective bargaining rights for most public employees.
Request rebuffed, they asked for Labor Secretary Hilda Solis.
So far, however, the White House has stayed away from trips to Madison, the state capital, or other states in the throes of union battles. The Obama administration is treading carefully on the contentious political issue that has led to a national debate about the power that public sector unions wield in negotiating wages and benefits.
A few labor leaders have complained openly that President Barack Obama is ignoring a campaign pledge he made to stand with unions; others say his public comments have been powerful enough.
The stakes are high as Obama looks toward his re-election campaign. Republicans have begun airing television ads linking Obama to "union bosses" standing in the way of budget cuts in Wisconsin, Ohio and other states.
As a candidate, Obama seemed to promise more to organized labor, among the Democratic Party's most loyal constituencies.
"If American workers are being denied their right to organize and collectively bargain when I'm in the White House, I'll put on a comfortable pair of shoes myself," Obama said at a speech in 2007. "I'll walk on that picket line with you as president of the United States of America because workers deserve to know that somebody is standing in their corner."
Rose Ann DeMoro, executive director of National Nurses United, the nation's largest nurses union, called Obama "largely a bystander" in the debate about collective bargaining. "I think we're feeling a sense of betrayal from him and not liking it much," she said.
Walker on Friday signed a bill that strips most collective bargaining rights from the state's public workers, except police and firefighters. The measure passed the Legislature following more than three weeks of protests that drew tens of thousands of people to the state Capitol in opposition. The governor had announced his plan on Feb. 11, saying his state was broke and there was no point negotiating with the unions when there was nothing to offer.