Former New York City mayor Michael Bloomberg has a stern message for anyone seeking the Oval Office in 2020: Get on board with environmentalism.

“I think that any candidate for federal office better darn well have a plan to deal with the problem that the Trump science advisers say could basically end this world,” he told Chuck Todd in an interview set to air Sunday on the NBC News program “Meet the Press.”

Bloomberg, who has established himself as an advocate for green initiatives, donating millions to the Paris climate agreement and slamming President Donald Trump for pulling out, warned that the next commander in chief must be prepared.

“The presidency is not an entry-level job,” said Bloomberg, who has acknowledged that he is considering running for president. “We have some real problems. If you don’t come in with some real concrete answers ― I think the public is tired of listening to the same platitudes that they get ― ‘We’re in favor of God, mother and apple pie, and trust me, I’ll have a plan when I get there.’ No. You have to have a plan.”

Despite the tough talk, Bloomberg has still not said whether he’ll throw his hat into the ring for 2020, continuing to avoid any sort of announcement on Todd’s show.

“I don’t know whether I’m going to run or not, but I will be out there demanding that anybody that’s running has a plan,” he said, adding that everyone should take a hard look at candidates’ ideas to evaluate their feasibility.