The 200 workers occupying Republic Windows and Doors in Chicago drew an influential supporter on the third day of their sit-in.
President-elect Barack Obama said at a news conference that the company should follow through on its commitments to the workers. They were abruptly fired last week and are seeking severance and vacation pay.
"The workers who are asking for the benefits and payments that they have earned, I think they're absolutely right, and understand that what's happening to them is reflective of what's happening across this economy," Obama said.
The workers peered through the windows of a door Sunday, amazed by a mix of supporters, politicians and journalists who packed a foyer outside. The Rev. Jesse Jackson also visited.
"We never expected this," said Melvin Maclin, a factory employee and vice president of the local union that represents the workers. "We expected to go to jail."
Leah Fried, an organizer with the United Electrical Workers, said the vinyl window manufacturer failed to give 60 days' notice required by law before shutting down.