WASHINGTON The U.S. House has passed and sent to the Senate a measure that would make it substantially easier for employees to unionize.

The Employee Free Choice Act, adopted by the House, is a union-supported bill opposed by business interests, and it carries the threat of a veto by President Bush.

The measure, known as H.B. 800, would allow the collection of a majority of pro-union vote cards to be sufficient to recognize a union in a workplace.

Under current law, unless an employer agrees to accept the "card-check" outcome, the National Labor Relations Board schedules and oversees a secret-ballot election, which usually happens 30 days to 50 days after the vote cards have been collected.

Card checks tend to favor union wins about 80 percent of the time, whereas unions tend to win secret ballots about half the time.

The secret ballot is designed to protect workers from employer intimidation, but union leaders say the intervening month to two months leaves employers free to discourage a "yes" vote by banning union organizers from the premises, threatening to close the business, or boosting pay and benefits. In 2005, more than 31,000 American workers illegally were disciplined or fired for union activity, according to the National Labor Relations Board.

"The current system is broken," said Jim Hoffa, general president of the Teamsters union. "Workers, after expressing their desire to form a union, usually endure nasty, bruising and lawyer-dominated elections, as the employer fights to block its employees' choice, often employing illegal tactics such as firing workers."

Critics say mandatory card checks will cost workers the secret ballot and leave them more open to intimidation, not less.

"The card check, by its very nature, makes a worker's vote completely and utterly public," wrote U.S. Rep. Howard McKeon, R-Calif., in a San Francisco Examiner editorial. "There's no way around it. Once that card is signed, everyone knows his or her vote the employer, union organizers, co-workers and the union bosses coordinating the whole process."

The bill also would impose new civil penalties against employers who "willfully or repeatedly" violated workers' rights to organize. The Bush administration said it is unfair to apply these penalties only to employers and not to union organizers guilty of intimidation.

Additionally, the bill would require binding arbitration, good for two years, if a new union cant agree with management on a new contract within three months.

Currently, 7 percent of private-sector employees in the United States are unionized, the lowest percentage on record. When government employees are counted, the percent of U.S. workers represented by unions is 12 percent. In recent polls, 58 percent of eligible Americans say they would join a union if they could.