WASHINGTON - The Democratic controlled US Senate on Thursday defeated a Republican sponsored amendment to turn back parts of President Barack Obama's healthcare reform.

The amendment, introduced by Republican Senator Roy Blunt to an unrelated highway bill, would exempt employers from providing employees free birth control coverage on moral and religious grounds. It was defeated in a vote of 51-48.

Three Democrats voted with Republicans, including Joe Manchin from West Virginia, Bob Casey from Pennsylvania and Ben Nelson from Nebraska. Casey and Manchin are both up for reelection in 2012.

Republican Olympia Snowe from Maine, who announced Tuesday she would retire at the end of this year, was the only Republican to vote in favor of tabling the amendment.

The amendment has gotten quite some media attention as social issues such as contraception have been heating up in the election cycle. Democrats argue the Blunt amendment was too broad, and maybe used in denying coverage on cancer treatments and other preventative treatments.

The White House requires employers to include contraception in their employees' healthcare plans without charging a co-pay or deductible, but exempts churches and houses of worship.

Religious-affiliated employers such as Catholic hospitals would not have to directly cover birth control in their healthcare plans, and the onus of providing their employees birth control coverage without a co-pay fell on the insurance companies.