Editors at the Wall Street Journal outline steps President Trump could take to boost his prospects in the 2020 campaign.

The paradox of Donald Trump’s Presidency after two years is that his main successes are the result of traditional Republican policies. His main trouble has come from the Trumpian exceptions on trade, immigration and polarizing temperament that motivate many of his supporters. Whether he can overcome that seeming contradiction may determine whether he can win what on present trends looks like an uphill climb to re-election. …

… Growth accelerated in 2017 amid deregulation and especially the end to the Obama harassment of business. The GOP Congress and Mr. Trump repealed no fewer than 16 costly Obama-era rules. Growth accelerated again to more than 3% on an annual basis in 2018 after tax reform—and may end up as the first calendar year above 3% since 2005.

Tax reform was mediocre on the individual side, with tax credits that redistributed income but did nothing for growth. But the tax-rate cuts for corporations and pass-through businesses were aimed specifically at the biggest weakness of the Obama expansion: capital investment, which surged in 2018. …

… Mr. Trump can help guard against an economic slump in the next two years by stepping back from his 2018 burst of protectionism. First, get as good a trade deal as he can with China, declare victory, and spend the next two years monitoring how well Beijing abides by its terms. …

… With an enhanced GOP Senate majority of 53, Mr. Trump can keep adding to another achievement—judicial nominees who are remaking the federal bench in the image of the late Justice Antonin Scalia. We wish Justice Ruth Bader Ginsburg well, but if illness forces her retirement Mr. Trump could cement what the last three GOP Presidents did not: an originalist majority on the U.S. Supreme Court for the first time in decades.