The American Trucking Association Inc., the leading lobbying group for the regulated trucking industry, is now telling members of the Senate that with two key changes they will drop their efforts to kill a deregulation package passed recently by the Senate Commerce Committee.

"If these changes are made, we will not be in the position of lobbying against final Senate passage," Bennett Whitlock, president of the association said yesterday. "We'll reserve judgement until we get further along.'

Whitlock said the ATA is opposed to a sweeping food exemption provision that would expand the exempt commodities truckers can carry to include all food products. Further, the ATA is firmly against deregulating freight moved partially by rail, another section of the Senate bill.

Whitlock also emphasized that the group would continue its staunch opposition to the bill if certain other amendments are added.

There have been some indications, for instance, that Sen. Edward Kennedy (D-Mass.), a long-time deregulation advocate, may propose from the Senate floor a total lifting of the antitrust immunity. In current form, the legislation would lift the immunity in 1983 only as it applies to single-line ratemaking.

Earlier in the day, John Kinnaird, ATA's vice president for government relations, suggested that the group possibly could support the bill if the two sections were lifted. "We would support it with some key amendments," he said at the time.

But Whitlock and Kinnaird later insisted that they will not support the bill under any circumstances when it comes to a vote on the Senate floor.

"We want the latitude," Whitlock said. "If those two provisions in the bill are removed, the industry will not oppose the bill."

The action ultimately taken on the Senate floor is vital to the fate of trucking deregulation since Rep. James Howard (D-N.J.), chairman of a House Public Works subcommittee considering measures to revise trucking statutes, seems inclined to wait until the full Senate acts before taking up the issue.

The Senate Commerce Committee passed a bill proposed by Sens. Packwood (R-Ore.) two weeks ago by a 13-to-4 vote. The Cannon-Packwood package does not go as far in deregulating the industry as does a proposal endorsed by President Carter, Kennedy and others.