WASHINGTON – In a rare show of industry solidarity, automakers and their dealers pressed Friday for Congress to block any attempt at allowing states to set their own fuel economy standards, laying a marker ahead of a new administration and Congress.

The action by the major domestic and international auto companies, as well as domestic and foreign-brand dealers, comes as more states consider whether to adopt California’s standards, which call for a fuel economy target of 42.5 miles per gallon average by 2020. The industry backed the bill approved by Congress last year setting a lower nationwide standard of 35 mpg by 2020, with terms that favored the industry’s approach to reaching the goal.

In December, the Environmental Protection Agency denied California’s request for a go-ahead on the limits, and officials from several states sued the EPA. At least 20 states have either adopted the California rules, aimed at reducing greenhouse gases linked to global warming, or debated doing so.

The auto industry has fought the state rules, saying they could force automakers to stop selling certain models, twist the industry to make unprofitable changes and create a menagerie of rules rather than one federal standard.

While the lawsuits slowly march on, California’s backers have launched bills in Congress to overturn the EPA. Few observers expect much action before the election, and all three major presidential candidates have said they back California.

The bills “may be posturing or leverage to create pressure on a new administration to grant the waiver,” said Dave McCurdy, head of the Alliance of Automobile Manufacturers, which includes Detroit’s automakers and Toyota.

Unlike other industries where companies often knot arms to rush Washington, the international scale of the auto industry has prevented much broad cooperation. In last year’s fuel economy debate, Detroit automakers and Toyota Motor Co. were the strongest backers, while Nissan Motor Co. gave some support to even tougher proposals and Honda Motor Co. stayed neutral.

Friday’s briefing included the AAM, the Alliance of International Automobile Manufacturers, the National Auto Dealers Association and the International Auto Dealers Association.

“This is one of the only times I ever remember having the entire industry, manufacturers and dealers, together on an issue,” said Mike Stanton, head of the AIAM and a three-decade Washington veteran.