Legislation making it easier for workers to join unions, a change opposed by companies such as Wal-Mart Stores and Starbucks, will be introduced by Democrats in Congress today.

The proposal will be offered in the House by Rep. George Miller, D-Concord, who heads the House Education and Labor Committee, and in the Senate by Tom Harkin, D-Iowa, said Aaron Albright, an aide to Miller.

The measure, known as the Employee Free Choice Act or the "card-check" bill, would allow a majority of workers to establish a union at a company by signing cards requesting representation, rather than having to hold a secret-ballot vote. Unions have made it their top goal in Congress this year.

"American workers understand very well the imbalances and greed that created the current economic downturn," Harkin, a member of the Senate labor committee, said in a statement. "This legislation puts power back into the hands of the people who are truly the backbone of this economy."

Labor groups say the current secret-ballot system for establishing unions invites employer intimidation. Businesses, including Wal-Mart and Starbucks, have said changing the law would let union officers pressure reluctant workers to sign the cards.

Labor leaders have said they expect the measure, endorsed by President Barack Obama, to become law this year.