President Trump is expected as soon as next week to order the Environmental Protection Agency to rescind its Clean Power rule that is blocked by the courts. But the President faces another test of political fortitude on whether to withdraw the U.S. from the Paris climate accord.

That’s suddenly uncertain. Mr. Trump promised to withdraw during the presidential campaign, correctly arguing that the accord gave “foreign bureaucrats control over how much energy we use.” His transition team even explored strategies for short-cutting the cumbersome, four-year process of getting out of the deal.

But the President’s is now getting resistance from his daughter, Ivanka, and Secretary of State Rex Tillerson, who are fretting about the diplomatic ramifications. No doubt many countries would object, and loudly, but this risk pales compared to the potential damage from staying in the accord.

President Obama committed as part of Paris to cutting U.S. emissions by 26% compared with 2005 levels by 2025. Even Mr. Obama’s climate regulatory programs—all imposed without Congressional votes—would only achieve about half that commitment. Mr. Trump is killing those Obama programs, which means the U.S. may not reach that Paris promise. Why stay in an agreement that the Trump Administration has no interest or plan for honoring?

Another risk is that the U.S. might at some point be coerced into compliance. Mr. Obama joined the accord without congressional assent and endorsed the lengthy withdrawal process precisely to bind future Administrations to his climate priorities. Since Mr. Trump’s election, the international climate lobbies have debated ways to muscle the new Administration to comply.