Democrats on Capitol Hill, together with labor groups and other allies, are waging an unusually aggressive campaign to derail the nomination of Andrew Puzder as labor secretary.
Mr. Puzder, chief executive of the company that franchises Hardee’s and Carl’s Jr. fast-food restaurants, has been a lightning rod as an outspoken foe of the Obama administration’s overtime regulation and the Affordable Care Act.
It is not clear how the Democrats intend to flip any Republican votes in the committee or in the full Senate, as they will need to do to defeat the nomination.
But if nothing else, the nomination battle has become a proxy for a larger struggle between labor and industry groups to shape public opinion on issues crucial to both.
In a forum that Senators Patty Murray and Elizabeth Warren organized earlier this week, one current and two former workers at one of the chains offered accounts of being denied proper overtime pay, and of being pressured to work off the clock and through breaks they were legally entitled to take.
On Thursday, fast-food workers and a variety of others protested Mr. Puzder’s nomination in more than a dozen cities across the country, in some cases at Hardee’s or Carl’s Jr. locations and in front of Department of Labor offices in others.
A spokesman for one of the organizers of the protest, the union-backed Fight for $15 minimum-wage campaign, said that thousands of workers had turned out.
Chuck Schumer, the Senate minority leader, made it clear that Mr. Puzder was one of the Democrats’ biggest targets in the confirmation hearings.
“Mr. Puzder has spent his career rigging the system against American workers by opposing the overtime rule, opposing the minimum wage, and underpaying his own workers,” he said in a statement. “His nomination as labor secretary is proof positive that the incoming administration won’t keep its promises to working people.”
Democrats and labor groups were heartened this week that the Senate panel overseeing his confirmation process, the Committee on Health, Education, Labor and Pensions, delayed the hearing for the second time, to an indeterminate date.
The session had been tentatively scheduled for Thursday and then tentatively rescheduled for next Tuesday.
But Senate Republicans and the Trump transition team said the delay in the confirmation hearing did not dim Mr. Puzder’s prospects.
Taylor Haulsee, a spokesman for Senator Lamar Alexander, the committee chairman, attributed the delay to “the complicated Senate calendar in January.”
A Trump transition official not authorized to speak on the record said that Mr. Puzder had submitted his paperwork to the Office of Government Ethics, which vets candidates for potential conflicts of interest, and that he had held meetings with senators this week and had more scheduled for next week.
The ethics office did not return multiple calls seeking elaboration on the status of the paperwork.
Industry lobbyists close to Mr. Puzder, the head of CKE Restaurants, complain that Democrats are spreading reports that the nomination is in trouble to build momentum against him.
“I think it’s complete spin; I think they are grasping at straws,” said Matthew Haller, senior vice president for public affairs and communications at the International Franchise Association, where Mr. Puzder was a board member until this month.
Mr. Haller said that the sophistication and intensity of the efforts against Mr. Puzder — which also include a slick website, antilaborsecretary.org — was predictable because labor groups had poured enormous resources into a campaign against the fast-food industry in recent years.
“From our perspective, the opposition groups are doing exactly what we expected them to,” he said. “They’ve been spending tens of millions of dollars attacking franchising, fast food, McDonald’s. That they can turn that playbook into this attack is not surprising.”
Tuesday’s Senate forum featured discussion of a survey of workers at Carl’s Jr. and Hardee’s by the progressive group Restaurant Opportunities Centers United in which many said they had been required to work uncompensated hours and most said they had come to work sick, either because their boss had not allowed them to stay home or because they could not afford to.
A group called the Employment Policies Institute, which receives funding from the restaurant industry, circulated a rival survey of Carl’s Jr. and Hardee’s employees in which a vast majority indicated that they felt “safe and respected” at work, and that “Carl’s Jr./Hardee’s is a great place to work.”
Each side disputed the survey methodology of the other.
Many industry lobbyists argued that Mr. Puzder was being mischaracterized as a conservative ideologue when in fact he is a pragmatic business leader.
“Andy has repeatedly said he’s not against a higher minimum wage,” said Cicely Simpson, executive vice president for government affairs and policy at the National Restaurant Association. “It just needs to be one that works for employees and employers alike.”
Mr. Puzder has opposed a $15 per hour minimum wage but said he favored “rationally” increasing the minimum wage.
Mr. Haller, of the International Franchise Association, said the group filled Mr. Puzder’s spot on its board on Thursday — an indication of its confidence in his confirmation prospects.
Still, Democrats and progressive activists suggested that there were issues beyond labor policy that could make Mr. Puzder’s hearings and confirmation vote contentious, even among certain Republican senators.
Not least, they said, were the company’s ads featuring skimpily attired models, which Mr. Puzder has enthused about publicly, and his record as an anti-abortion activist in the 1980s, when he helped write a Missouri law banning the procedure at public facilities and forcing doctors to conduct viability tests at 20 weeks.
“There’s a broad base of concern — most low-wage workers in this country are women,” said Minor Sinclair, the head of the Decent Work program in the United States at the antipoverty group Oxfam, which is opposing Mr. Puzder’s nomination. “He portrays demeaning ads toward women, the objectification of women, to sell his burgers.”