WASHINGTON —

As two federal regulators asked a House panel to tighten proposed legislation imposing new oversight on derivatives, Republican lawmakers contended the measure already could eliminate jobs and stifle companies’ ability to manage risks.

A potent new coalition of about 170 companies that use derivatives — including Boeing Co., Caterpillar Inc., Ford Motor Co., General Electric Co. and Shell Oil Co. — is lobbying Congress to make the case that legislative proposals to regulate the complex financial instruments could severely increase costs for corporate America.

"The end-user community has been constantly knocking on my door," Rep. Frank Lucas, R-Okla., said at a Financial Services Committee hearing.

Rep. Barney Frank, D-Mass., the committee’s chairman, stressed that the proposal he put forward is "a work in progress." He acknowledged that there may be "gaps" in some areas in the draft as written.

Final legislation isn’t likely to clear Congress and land on President Barack Obama’s desk until December at the earliest, Frank said. It is considered to be less stringent than the administration’s proposal for new oversight on derivatives, traded in a $600 trillion unregulated global market and blamed by regulators for hastening the financial crisis.

Frank’s proposal is an improvement over the administration plan but still includes "potentially troublesome" requirements, said Rep. Spencer Bachus of Alabama, the committee’s senior Republican. "Any new regulation should not hamper the ability of businesses to control costs, manage risks, compete in the global marketplace and create jobs," he said.

But fellow Democrat Mel Watt of North Carolina said Frank’s proposal may not be strict enough and "may have tilted us in a direction that is more contrary to what we are trying to achieve." For example, the measure may have created loopholes that would allow some big financial firms that deal in credit swaps to skirt regulations, he said.

The proposals are designed to bring transparency to, and prevent manipulation in the sprawling derivatives market. Credit default swaps, a form of insurance against loan defaults, account for an estimated $60 trillion of that market. The collapse of the swaps brought the downfall of Wall Street banking house Lehman Brothers Holdings Inc. and nearly toppled American International Group Inc. last fall, prompting the government to support the insurance conglomerate with about $180 billion in aid.

The value of derivatives hinges on an underlying investment or commodity — such as currency rates, oil futures or interest rates. The derivative is designed to reduce the risk of loss from the underlying asset.

Gary Gensler, the chairman of the Commodity Futures Trading Commission, called Frank’s proposal "an important contribution" toward achieving comprehensive oversight of derivatives but urged changes "to ensure that we cover the entire marketplace without exception."

"The American public needs to benefit from the full transparency" that would come from mandating most derivatives go through a new network of clearinghouses and be traded on regulated exchanges, he said.

Henry Hu, director of the Securities and Exchange Commission’s new division of risk, strategy and financial innovation, said the proposal as written "could unintentionally preserve existing regulatory gaps."

"Relatively simple changes to the discussion draft would ensure that the legislation results in the improved supervision" of the derivatives market, Hu testified