The US Senate on Tuesday rejected an anti-abortion amendment to a health care reform bill, splitting the Democrats and complicating the chances of getting a 60-vote majority to pass the measure.

The amendment barring federal funds from being used to pay for abortion, directly or indirectly, was defeated by a 54-45 vote.

It was supported by Democrats Robert Casey and Ben Nelson, author of the amendment, and eight Republican senators, including amendment co-author Orrin Hatch.

Nelson's measure would prohibit Americans who receive government subsidies to pay for health care from buying into an insurance plan that covers abortion, and would ban a government-backed insurance plan popularly known as a "public option" from covering the procedure.

The measure includes exceptions in cases of rape, incest, or where a doctor certifies that the woman is "in danger of death unless an abortion is performed."

Tuesday's vote could complicate Senate Majority Leader Harry Reid's plan to muster the 60-vote margin needed to pass the health care bill before the end of the year.

Some lawmakers have already said they will not vote in favor of the reform legislation unless it includes an anti-abortion measure.

The anti-abortion amendment mirrors a similar proposal that the House of Representatives attached to its version of the health care bill passed November 7, despite expectations that House and Senate negotiators might strip it out later in the legislative process.

The White House-backed health care bill aims to extend coverage to some 31 million Americans out of the roughly 36 million who currently lack it, while curbing soaring costs and improving the quality of care.