(Bloomberg) -- The Biden administration plans to announce new limits on greenhouse gas auto emissions and new electric vehicle sales targets at an event with Detroit automakers at the White House on Thursday, according to several people familiar with the matter.

The mandates are a centerpiece of President Joe Biden’s climate plans and mark his administration’s first major effort to use regulation to stem planet-warming greenhouse gases. The limits are likely to fall short of what environmentalists have called for, while pleasing auto manufacturers.

The standards, drafted by the Environmental Protection Agency, would be patterned on a compromise automakers reached with California regulators two years ago -- rather than the tougher mandates charted by former President Barack Obama in 2012, according to the people, who requested anonymity to discuss the plan before it is made public.

The announcement, which will be attended by representatives of some Detroit automakers, is expected include a commitment from auto manufacturers to target at least 40% of sales as electric vehicles by 2030, according to two of the people. The people asked not to be identified prior to the announcement.

A spokesperson for General Motors Co. had no comment. Representatives of Ford Motor Co. and Stellantis NV could not immediately be reached.

Activists had pressed Biden for emissions curbs as strong as those he helped broker as Obama’s vice president, which mandated a 5% reduction annually. That would have led to a fleet-wide average of almost 50 miles (80.47 kilometers) per gallon in 2025.

Environmentalists and some electric-vehicle manufactures are preparing for disappointment based on earlier drafts of the plan.

“This draft proposal would drive us in the right direction after several years in reverse -- but slowly getting back on track is not enough,” Chris Nevers, senior director of environmental policy at electric vehicle maker Rivian Automotive Inc., said in response to reports of the standards. The Biden administration “must maximize the stringency of the program beyond the voluntary deal and account for current and future developments in vehicle electrification.”

The emissions mandates come as federal regulators are developing additional rules targeting methane emissions from oil wells and carbon dioxide releases from power plants, after the Trump administration relaxed requirements.

Representatives of the White House and Environmental Protection Agency declined to comment and a representative of the National Highway Traffic Safety Administration didn’t respond to a request for comment.

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