As U.S. automakers prepare to submit turnaround plans to Congress, a prominent Senate backer of federal aid for the ailing industry on Monday questioned whether lawmakers have enough expertise on their own to make a determination about the industry’s viability.

Sen. George V. Voinovich , R-Ohio, also expressed concern about whether proprietary information submitted by the Big Three will be protected from disclosure. Voinovich, part of a bipartisan group of senators who unsuccessfully pushed a plan last month for up to $25 billion in federal loans to Detroit, expressed his views in a letter to House Speaker Nancy Pelosi , D-Calif., and Senate Majority Leader Harry Reid , D-Nev.

Pelosi and Reid have asked the heads of General Motors Corp., Ford Motor Co. and Chrysler LLC to provide detailed plans by Tuesday outlining their strategies for remaining viable in the face of falling profits and increased competition.

“While I applaud your insistence that the potential borrowers prove their case, however, I am concerned about the method you have constructed for doing so,” Voinovich wrote. “Specifically, I question your decision that congressional leadership and committees of jurisdiction are best positioned to make determinations about a multinational corporation’s future financial prospects.”

He asked whether lawmakers would consult outside experts and executive branch officials “or do you feel that Congress is qualified to draw such conclusions?”

The Ohio senator also questioned whether Reid and Pelosi were prepared to safeguard information in the plans that the industry considers proprietary.

The submission of the plans is expected to touch off a week of intense lobbying by the industry and its backers, including the United Auto Workers union, for a federal lifeline. The Senate Banking Committee has scheduled a hearing on the plans for Dec. 4, with the House Financial Services Committee following on Dec. 5.

Pelosi has said Congress could take up bailout legislation on Dec. 9 or Dec. 10 if lawmakers are convinced that the package would be an “investment in their viability” by taxpayers and not “life support for a few months and then they’re back again.”