The Republican-controlled U.S. Senate has passed legislation to cut the federal deficit by nearly $40 billion over the next five years by the narrowest of margins - a 51 to 50 vote.

Vice President Dick Cheney cast the deciding vote for the Republicans. He had been traveling in South Asia and cut short his trip to return to Washington in case his vote was needed.

The legislation includes cuts to social welfare programs such as health care for the poor and the elderly. But during debate in the Senate, Democrats forced a minor change to the bill which will need approval of the House of Representatives. The House approved the original measure on Monday, and many members have now left town for the Christmas, Hanukkah and New Year's holidays.

Also up for a vote Wednesday is a mammoth defense spending bill - a package costing more than $450 billion that includes a controversial provision to allow oil drilling in Alaska's wildlife refuge.

Some information for this report provided by AP and Reuters.