"A Bush volunteer attempted first to shut the door against the protesters, then to push out several, including Jon Youngdahl of the Minnesota AFL-CIO, who struggled to yell through his bullhorn while the volunteer kept searching for a mute button on it," the paper said.

Three hundred workers were bused in for the demonstration by Minnesota labor unions, with about a dozen protesters forcing their way into the building.

As the ruckus raged inside, demonstrators outside chanted, "George Bush, go away, don't take away my overtime pay."

Diane O'Brien, spokeswoman for the Minnesota AFL-CIO, said the group was trying to deliver 10,000 postcards complaining about the overtime changes. "We want to send a message to the president," she said.

Led by Rep. Tom Feeney, R-Fla., 50 GOP congressman have signed a letter requesting a Justice Department investigation into protests like the one in Minnesota, to see if they are part of a coordinated effort to violate federal election laws.

Brian Thomasen contributed to this report.

Editor's note: