House and Senate negotiators have tucked a potentially far-reaching anti-abortion provision into a $388 billion must-pass spending bill, complicating plans for Congress to wrap up its business and adjourn for the year.

The provision may be an early indication of the growing political muscle of social conservatives who provided crucial support for Republican candidates, including President Bush, in the election.

Federal law now says that hospitals and health care providers who receive taxpayer money must offer abortion counseling to women who ask about it. Catholic hospitals are now exempt from the law; the provision in the spending bill would allow all hospitals and health care providers to refuse to comply.

The language would also allow hospitals and health care providers to opt out of state and local laws that require them to provide abortions, abortion counseling or referrals.

"It's something we've had a longstanding interest in," said Douglas Johnson, a spokesman for the National Right to Life Committee. He added, "This is in response to an orchestrated campaign by pro-abortion groups across the country to use government agencies to coerce health care providers to participate in abortions."

On Friday, eight female senators - seven Democrats and one Republican, Olympia J. Snowe of Maine - wrote a letter to Senator Stevens asking that the language be changed and complaining that it had not gone through committee or to the Senate floor for a vote...

Lawmakers in the House and the Senate intended to vote on the omnibus bill on Saturday, when a stopgap spending measure is set to expire at midnight. Congress failed to pass 9 of its 13 required spending bills before recessing for the election, leaving much of the government - with the exception of the Pentagon and the Department of Homeland Security - to operate under the interim measure.