WASHINGTON — The Trump administration threatened to withhold highway funds from California, arguing the state failed to show what steps it’s taking to improve air quality. The move by the Environmental Protection Agency escalates the battle between President Trump and the state and could put billions in federal funds in jeopardy.

EPA Administrator Andrew Wheeler suggested the state ‘‘has failed to carry out its most basic tasks under the Clean Air Act’’ and needs to update its plans.

‘‘California has the worst air quality in the United States,’’ Wheeler wrote.