Democrats in the Senate are scrambling to draft an auto industry relief bill that can win over skeptical Republicans when the measure comes up for a vote next week.

Senate Majority Leader Harry Reid and supporters of the bill, which would extend $25 billion in emergency loans to the auto industry, are trying to round up the votes needed to break an expected filibuster. Reid plans to begin debate Monday and set up a test vote on Wednesday.

But Democrats will have to do a lot of arm-twisting before then. Supporters expect to need between 12 and 15 GOP votes to attach the measure to a $6 billion bill the House passed in October that would extend jobless benefits. So far, they have only one firm commitment, from Sen. George Voinovich of Ohio, a state with several auto plants and auto-supply manufacturers.

In a letter Friday to Senate Minority Leader Mitch McConnell, Reid urged Republicans to reconsider their opposition.

"In my view, the adoption of a robust recovery package should be the top priority of the upcoming lame duck session," Reid wrote. "That is why I intend to seek consent on a bill to create jobs, prevent large tax increases and cuts in state services, strengthen our nation’s manufacturing sector, and assist those struggling to find a job."

Sen. Chris Dodd, D-Conn., chairman of the Senate Banking, Housing and Urban Affairs Committee, was skeptical Thursday about gaining Republican support for an auto rescue bill. "Right now, I don't think there are the votes," Dodd said.

Democrats are already expected to be down one vote, with President-elect Barack Obama planning to make his resignation from the Senate effective Sunday.

And Republicans are reluctant to commit to the bill. One senior Senate Republican aide told FOX News, "This is all very nebulous. There is still no bill. It pre-supposes there is full Democratic support."

McConnell, R-Ky., told FOX News it's "unclear" what would be in the bill.

Democrats could include items like extra stimulus measures and low-income heating assistance.

Jim Manley, Reid's spokesman, noted Thursday night that nothing can be done without the agreement of Senate Republicans.

But Sen. Carl M. Levin, D-Mich., said he was "confident that there will be bipartisan support for legislation to support the U.S. auto industry."

Reid, D-Nev., rejected Dodd's suggestion to wait until next year, when Democrats will have bigger majorities in the House and Senate, as well as a Democratic president in the White House.

Meanwhile, the House plans to meet at 1 p.m. ET on Wednesday for a potential lame-duck session, where they could consider the loan package as well as an economic stimulus plan. But the House could also abandon that plan if the Senate is clearly unable to move forward its version of the auto rescue package.

Democrats would have no problem passing the bill in the House, where they have a much larger majority than the narrow 50-49 one they will have in the Senate once Obama resigns.

The bill would carve out part of the $700 billion Wall Street bailout for loans to the Big Three U.S. auto companies. The measure would provide for the government to hold some kind of ownership stake in the companies for the duration of the loan to ensure that taxpayers shared in any gain and would ultimately be reimbursed.

Citing an economic downturn that has choked off sales and frozen credit, General Motors Corp., Ford Motor Co. and Chrysler LLC are lobbying feverishly for Congress to approve the aid.

The White House on Friday threw its support behind a plan to speed release of $25 billion in existing loans to the three main U.S. automakers but rejected the Democratic proposal to use money from the financial bailout to help the troubled industry.

McConnell of Kentucky — home to General Motors and Ford plants — has been noncommittal about new aid. His office says Congress should instead revise a $25 billion loan program it approved last month to speed the release of the money, which is designed to help automakers develop more fuel-efficient vehicles. This idea is endorsed by the White House and Treasury Secretary Henry Paulson.

Some Senate Republicans are skeptical the aid under the auto proposal would lead to changes by the companies that could make them viable in the long run. But several states with Republican senators have Big Three auto factories.

"Spending billions of additional federal tax dollars with no promises to reform the root causes crippling automakers' competitiveness around the world is neither fair to taxpayers nor sound fiscal policy," House Minority Leader John Boehner, R-Ohio, said in announcing his opposition to the measure.

Supporters of the auto bailout are targeting lawmakers who represent states with auto plants and auto suppliers, as well as Republicans in states with high unemployment rates.

Sen. Kit Bond, R-Mo., left open the possibility that he could be persuaded to back a carmaker rescue. "While I have real concerns with another taxpayer funded bailout, there are also thousands of workers in Missouri whose jobs are on the line, so the devil will be in the details," Bond said in a statement.

Lawmakers in both houses will be in Washington next week to reorganize their leadership teams and committee assignments for the 111th Congress, which convenes on Jan. 6.

The bill Democrats are writing would insert the government squarely into the car companies' operations. It would require that the companies submit a plan for long-term viability in exchange for the loans, share a portion of future profits with the government and reimburse taxpayers before any other shareholder, according to aides familiar with it.

"We certainly want to make sure that there's a plan how are you going to get out of this mess," said Sen. Chuck Schumer, D-N.Y.

The car companies also would face tougher restrictions on pay for their executives and dividends for their shareholders than did the financial companies that got a piece of the original bailout.

FOX News' Chad Pergram and The Associated Press contributed to this report.