U.S. Sen. Tom Harkin, who sponsored legislation to make it easier for workers to join unions, has said the main provision of the proposal may have to be dropped to get the votes to pass it.

There is not enough support for a provision called card-check that would allow workers to bypass an election and form a union when a majority of them sign cards requesting one, Harkin said yesterday in an interview.

"Compromises are going to be made," said Harkin, an Iowa Democrat. "It probably won't be card-check, because too many people are opposed to it now."

The legislation stalled in the Senate after several lawmakers whose votes would be needed to overcome Republican opposition, such as Sen. Blanche Lincoln, an Arkansas Democrat, said they would not support the measure. Companies such as Wal-Mart Stores Inc., of Bentonville, Ark., have led opposition.

Harkin said he hoped changes to the bill would gain "maybe the grudging support of labor and maybe the grudging support of some businesses."

Labor groups spent $100 million last year to elect Democrats and have made passing the card-check measure their top goal in Washington this year. President Obama supports the bill. The legislation doesn't have enough backing in the Senate to overcome efforts by Republican opponents to block a vote.

A softened version of the bill may attract support from more lawmakers, Harkin said.

"Many do feel there is an imbalance" in current laws that favor business over labor, Harkin said.

"They may not be for the card-check, but they are for changing election process and procedures and shortening the period of time for elections" to form unions in a company.