(POLITICO) President Barack Obama on Tuesday will order his agencies to tighten the fuel-efficiency standards for medium- and heavy-duty vehicles, the latest stage in his effort to tackle climate change without waiting for Congress to act.

During a visit Tuesday morning to a Safeway distribution center in Upper Marlboro, Md., Obama will announce he’s directing the Environmental Protection Agency and the Transportation Department to develop fuel-efficiency and greenhouse gas standards for future trucks and other heavier vehicles by March 2016. They would cover vehicles for model years after 2018.

Tighter post-2018 standards for heavy-duty vehicles, which account for about a quarter of onroad greenhouse gas emissions from the transportation sector, were part of the list of items Obama laid out in June in his climate action plan. The new requirements follow up on standards the administration imposed three years ago for heavier vehicles from model years 2014-18.

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