Union officials do not want their options limited to a secret-ballot election.

Cintas has not given in, insisting that secret-ballot elections are fairer.

"That's not a reason to replace the fairest process, secret-ballot elections."

Under the bill, workers would choose to unionize through card checks or a secret-ballot election.

"We have made the choice not to force these employees to join the union without a proper secret-ballot election," Ms. Brown said.

Under current law, employers can insist on a secret-ballot election to determine whether a majority of employees favors a union.

The companies would be required to hold secret-ballot elections that must be certified by an independent third party.

But industry officials say that it is more democratic for workers to choose whether they want a union through secret-ballot elections.

Under current procedures, a company may insist that its workers vote in a secret-ballot election to determine whether they want to be represented by a union.

Under current law, companies have a right to insist on a secret-ballot election determining their workers' choice.