COLUMBUS, OHIO - The Ohio Senate on Wednesday narrowly approved a sweeping bill that would weaken the powers of public employee unions to negotiate contracts, propelling Ohio into the vanguard of states seeking to revise public-sector labor laws.

The vote came as union supporters protested the measure for a second day on the grounds of the Statehouse in Columbus. The GOP-sponsored bill passed the Senate 17 to 16, with six Republicans voting against it.

As the roll call finished, dozens of union supporters in the Senate gallery chanted "Shame! Shame! Shame!" Screeches and shouts echoed down the corridors of the Statehouse, where hundreds of opponents of the bill had gathered for the day's events.

The bill next goes to the House, where it is expected to pass, and then to the desk of Republican Gov. John Kasich, who is expected to sign it.

"Thousands remain unemployed," Sen. Shannon Jones (R), the bill's author, said on the chamber floor Wednesday. "Companies are leaving our state. Financially, our state and local governments are at the breaking point. Revenues are on the decline. Demand for services is on the rise. And the cost of government is growing beyond the ability to sustain it."

By including police and firefighters unions, Jones's bill goes further than a better-known one under consideration in Wisconsin. There, Gov. Scott Walker (R) has gained national attention by railing against the power of public unions, but he exempted police and firemen from his plan to strip collective bargaining rights.

Ohio Republicans revised the bill to restore collective bargaining on the issues of wages, hours, and certain terms and conditions, but they also extended an existing ban on strikes to include teachers, and they blocked binding arbitration, giving the final say in contract disputes to government.

Union organizers and their allies said the changes don't go far enough to maintain workers' ability to bargain on a wide range of contractual issues, including pensions, health benefits and such safety matters as equipment for police officers and firefighters. Making strikes illegal for all public workers, they said, effectively neutralizes the power of collective bargaining and gives workers no incentive to come to the table.

"This bill provides for our safety to be contracted out to the lowest bidder," said Jay McDonald, president of the Ohio Fraternal Order of Police. "As a public safety professional, I rely on equipment to save my life. . . . When we begin to compromise my ability to talk to my employer about things that directly affect my safety, you have crossed the line."

Opponents of the legislation said they are already planning to fight it with a ballot challenge this fall. If it gathers enough signatures, the challenge would give voters a direct say on the measure in November.

On Tuesday, more than 8,000 union supporters descended on the Statehouse in protest. Like their counterparts in Wisconsin, demonstrators here accused lawmakers and Kasich of trying to use a budget crisis to destroy public-sector unions. Government workers did not cause the crisis and should not bear the brunt of it, protesters said.

But unlike in Wisconsin, Democratic lawmakers here did not have the numbers to delay a vote through a walkout.