Sen. Ben Nelson, D-Neb., voted against the bill that would, among other measures, give employers an immediate break on Social Security taxes for new hires through the rest of the year.
Sen. Scott Brown, R-Mass, who took over the late Edward Kennedy's seat in a special election in January, taking a procedural advantage away from the Democrats, was one of the Republicans who voted for the bill, The Washington Post reported.
There has already been some whiplash from Brown's vote with conservative bloggers labeling him a "sellout" on his Facebook page, the newspaper said.
Majority leader Harry Reid of Nevada said he was "very happy" with Brown's vote.
The bill now heads to the House for approval, although House members could try to merge the bill with a $154 billion jobs bill passed in that chamber in December.