The EPA's plans to freeze fuel economy and emissions standards have been put on hold until at least Labor Day, sources familiar with the plans told Bloomberg earlier this week.

Last August, the EPA released its long-anticipated proposal to unwind the steadily rising fuel-economy standards put in place in 2012 under President Obama, in part to combat growing emissions of carbon dioxide, which contributes to climate change.

The plan proposes to freeze those fuel economy increases at 2020 levels through 2026, requiring cars and trucks to average about 37 mpg, rather than increase them to 47 mpg by 2025 as current law requires.

In days after Donald Trump was elected President, automaker lobbyists met with the President-elect to lobby for loosened standards, arguing they need a single national standard, not one that accommodates California-compliant states separately and different compliance rules between the EPA and NHTSA.

Under federal law, California has been allowed to set stricter emissions standards. Yet the standards have never been as unified before as they are under the current law.

This isn't the first time that the timeline has changed. Early this year, EPA Administrator Andrew Wheeler revealed in a Bloomberg interview that the agency expected to release the new rules by April. After receiving a lot of negative comments on the proposal, especially from some unexpected quarters, Wheeler announced in April that the proposal would be revised and targeted a new release for June. The revised proposal was expected to require small increases in fuel economy through 2025.

Now both automakers and the Governors of 23 states, including some red electoral bastions and several purple battlegrounds that President Trump relied on in his election, have released public letters opposing the freeze in standards. California, with 17 other states, has sued the EPA over the proposal's plan to rescind its EPA waiver, and to attack its future right to set its own standards. 

If the standards are frozen, that lawsuit would likely move forward in court and lead to years of division in state standards and uncertainty for automakers. Since automakers are already developing cars for the 2023 model year and beyond, that uncertainty would certainly be costly,

With the President already starting to campaign for the 2020 election and parties on almost all sides opposed to the proposal, the summer delay could lead to an even longer delay.