A national group representing auto dealers on Monday withdrew its opposition to General Motors Corp.'s (GM) effort to ink new contracts with dealers who aren't on the auto maker's closing list.

The National Automobile Dealers Association had been protesting contracts GM sent to thousands of dealers last week who are among those the auto maker wants to stay in business.

The group said GM imposed unfair restrictions on those being offered to stay, including what it saw as unmanageable or unclear requirements to upgrade dealerships, meet sales and performance goals and restrictions on having stores that combine GM and non-GM brand dealerships, NADA spokesman David Hyatt said Monday.

GM agreed to amend the offers enough to ease the dealer associations' worries, Hyatt said.

A GM spokesperson could not immediately be reached.

The auto maker is moving to eliminate around 40% of its dealer network in bankruptcy court. GM is asking all of its roughly 6,000 dealers to decide by Friday whether to accept offers to either close or stay in business. Many dealers marked to close are protesting GM's decision either legally or on Capitol Hill.

GM has argued it overspends to support and oversized dealer network, which would produce better sales results if it included fewer, healthier dealerships.

-By Sharon Terlep; Dow Jones Newswires; 248-204-5532; sharon.terlep@dowjones.com