California officials said Wednesday that theyre prepared to fight President Donald Trump over his announcement that hes revoking the states legal authority to set its own car emissions standards.

At a press conference, state leaders emphasized that theyve long anticipated this move by the Trump administration and that they plan to take Trump to court over it as soon as possible.

This is the fight of a lifetime for us. We have to win this, California Air Resources Board chairwoman Mary Nichols said, adding that shes been paying her dues to the State Bar of California just in readiness for this moment, so that she could be part of the litigation.

Shortly before she spoke, Trump tweeted out confirmation that he was revoking a waiver thats long allowed the state to establish its own tailpipe emissions policy, upending decades of bipartisan support for that exception.

The president argued that revoking the waiver would make cars cheaper and safer while making little difference in emissions and creating more jobs.

This is simply inaccurate, Democratic Gov. Gavin Newsom retorted on Twitter , saying the looser standards Trump wants would cost consumers $400 billion and result in 320 billion more gallons of oil burned and spewed into our air.

He elaborated at Wednesdays press conference, accusing Trump of being in oil companies pockets.

Its about the oil industry, period, Newsom said. Its not about the car manufacturers, not about consumers. ... Its not about our economy. Its about oil companies.

Car makers are also on board with Californias standards, which landed four of the biggest brands in the industry in a public spat with Trump last month after they reached a voluntary agreement with California on fuel efficiency rules.

Trumps refusal to acknowledge that human activities like driving are causing climate change remains at the center of this fight.

We cannot afford to backslide in our battle against climate change, California Attorney General Xavier Becerra said Wednesday. For us, this is about survival. Our communities are screaming for help to address the climate crisis. Unlike the Trump administration, we dont run scared.