In a procedural vote seen as a gauge of support for President Barack Obama's $447 billion jobs package, 50 U.S. Senate Democrats Tuesday backed an effort to let the plan proceed, but there was not enough support to meet a 60-vote threshold.

All but two Democratic senators--Jon Tester of Montana and Ben Nelson of Nebraska--voted to end debate on the American Jobs Act and allow the legislation to advance. Meanwhile, all but one Republican, Sen. Tom Coburn of Oklahoma, who was unable to vote, unanimously voted to maintain their filibuster.

The unofficial tally is 50 to 48 as of Tuesday evening because it was held open to give time for Sen. Jeanne Shaheen, D-N.H., to get to Washington from Boston. She will cast the 51st vote for the measure, a spokesman told the New Hampshire Union Leader.

Could Become 2012 Election Issue

Obama could capitalize on the Senate vote as he pitches his jobs bill in public appearances around the U.S. With a majority of senators backing his jobs proposal, he can continue to argue that Republicans were blocking a jobs bill that is needed to begin bringing down a 9.1 percent unemployment rate.

Earlier on Tuesday, Obama was in Pittsburgh to discuss his jobs bill, telling an audience that senators who vote against the bill would have a hard time explaining why they voted no for this bill other than for the fact that I proposed it, according to

While Democratic senators have given some overall praise to Obama's jobs plan, several were able find something to criticize, preventing them from supporting the legislation as a whole. There were, however, yes votes on Tuesday evening who said they would vote against the full jobs plan.

The Senate may eventually break the bill up into smaller parts, allowing more palatable parts of the package. The leadership in the Republican-controlled U.S. House of Representatives also wants the bill in pieces.

The American Jobs Act is a mix of tax cuts, tax incentives and new spending to prevent teacher layoffs and employ construction workers on infrastructure projects.

To cover the plan's cost, Obama proposed eliminating tax breaks for oil companies, taxing as regular income hedge fund managers' capital gains and restricting tax deductions on households making $250,000 a year or more.

Sen. Majority Leader Harry Reid's own proposal to pay for jobs bill is to institute a 5.6 percent tax surcharge on those making a million dollars a year or more. Obama said last week he was comfortable with Reid's plan.