The Republican-run Senate Appropriations Committee approved the provision blocking the rules by a vote of 16-13. Two Republicans — Sen. Arlen Specter of Pennsylvania, who is seeking re-election this year, and Ben Nighthorse Campbell of Colorado, who is retiring — joined Democrats in supporting the proposal.
The language was offered by Sen. Tom Harkin, D- Iowa, who said new Bush administration overtime rules that took effect on Aug. 23 would deny the extra pay to many workers who had received it.
Harkin said the new rules are "anti-worker, anti-job growth, and anything but family friendly."
Sen. Judd Gregg, R-N.H. said the estimate of 6 million workers losing overtime was "totally bogus." And the committee's chairman, Ted Stevens, R-Alaska, argued that the new rules should be left in effect for a while so their impact can be judged.
The overtime provision was added to a $145.9 billion spending bill financing labor, health and education programs. The overall measure was approved by a 29-0 vote.
The committee's action was Congress' second embarrassing rebuke to Mr. Bush in a week on the issue, and underscored the sensitivity of Republicans from labor districts have on overtime.
Last Thursday, the GOP-led House voted 223-193 to prevent the Labor Department from carrying out the new rules.
The White House has threatened a veto if the overtime language attached to the spending bill survives. House leaders said they believe the provision will be removed when House-Senate bargainers write a final version of the legislation.
Democrats and their labor allies say the new regulations would hurt 6 million workers. They say chefs, nurses, police officers, journalists, athletic trainers, lower-level computer employees and those who perform small amounts of supervisory work would be among those whose employers could stop paying them overtime.
That is disputed by the White House and the Labor Department, which argue that the new rules clarify who is entitled to overtime and would reduce confusion that has led to expensive lawsuits.
The Bush administration says about 107,000 white-collar workers making $100,000 or more could lose eligibility.
The new regulations — the most dramatic overhaul of overtime rules in five decades — also would require overtime pay for workers earning up to $23,660. That is triple the annual salary above which overtime was previously required, an increase the Labor Department said would protect 1.3 million workers.
Harkin's amendment would allow those extra workers to get overtime, and would only affect those who stood to lose it.
The Labor Department says the changes are necessary to update the law to reflect today's workforce.
Labor Secretary Elaine Chao revised the regulations substantially over a draft issued a year ago after Republican lawmakers complained that police, firefighters and others could lose overtime eligibility.
Democrats and organized labor said that despite the revisions, millions of workers in dozens of occupations, including police sergeants, could lose overtime coverage.
The regulations took effect in August. Barring a reversal in the administration's position, critics trying to block the rules have many formidable obstacles to overcome.
The federal overtime law requires that employees be paid overtime unless they meet three tests: they must be paid more than a certain amount, be paid a salary rather than an hourly wage and perform certain duties.
The Bush administration is raising the salary ceiling from $155 a week to $455 a week. That will increase the number of workers covered.
What is in dispute is how many more workers will be exempt from overtime pay because of the way the administration is redefining which categories of workers are covered.
A July report by the liberal Economic Policy Institute estimated that among those who would lose overtime protection were nearly 2 million administrative workers who can be classified as "team leaders" and 920,000 workers who can be reclassified as a "learned professional" even though they do not have college degrees.
EPI says the administration's proposal would deny pay to an employee who "leads a team of other employees assigned to complete major projects for the employer."
The EPI study also said 1.4 million workers who, because of the rules changes, can be reclassified as executives will lose overtime pay as will an estimated 130,000 chefs and cooks, 160,000 financial service workers and 117,000 teachers and computer programmers.
A separate report by the three former Labor Department officials said the rules change impact was likely to be significant because "more classes of workers and a greater proportion of the work force overall will be exempt than we believe the Congress could have originally intended."