Kevin Hassett, the chairman of the Council of Economic Advisers, is leaving the administration, President Trump announced on Twitter on Sunday night. No reason was given for Hassett’s departure, and Trump said his successor will be named as soon as Trump returns from his trip to the U.K. The conservative economist was the architect of Trump’s merit-based immigration plan. Last month, Hassett predicted the expansion of the economy would continue—possibly at an even greater pace—through 2019. Last year, he oversaw a council report that said tariffs would hit U.S. consumers in their wallets.