Certain business leaders and prominent conservatives have denounced Donald Trump’s economic policies and even argued that Hillary Clinton would be a better choice in November. This is hard to fathom. Although we disagree with him on some issues, we have both signed on as economic advisers to Mr. Trump because we are confident in the direction he would take the country. What could possibly be the economic case for Mrs. Clinton? She has vowed to defend President Obama’s “legacy” and double down on job-killers like ObamaCare. Even Bill Clinton knows that the status quo hasn’t worked: In March he told a crowd that it is time to “put the awful legacy of the last eight years behind us.”Since the end of the recession, economic growth has averaged an anemic 2.1%, producing the weakest “recovery” since the Great Depression. That has slowed to 1.4% in the last quarter of 2015 and 1.1% in the first quarter of 2016. The middle class is shrinking, and median household income today, in real terms, is lower than when Mr. Obama took office. By more than two to one, Americans believe the country is on the wrong track. What does Mr. Trump offer as an alternative?The biggest pro-growth tax cut since Ronald Reagan’s 1981 reform. Mr. Trump would simplify the tax code and significantly reduce marginal rates, encouraging investment and economic expansion. His proposed corporate tax rate of 15% would make it easier for American firms to repatriate earnings, bringing capital home and making the US a more hospitable place to invest. Mr. Trump’s tax plan would do more for working-class and middle-class families than any scheme to redistribute income. Don’t believe the phony claim that it will cost $10 trillion over a decade. As Americans will see when he reveals the entire plan in the next few weeks, any revenue loss would be a fraction of that amount.The repeal of ObamaCare, the fastest-growing entitlement program of all. Mr. Trump promises to replace the law with a consumer-choice health plan. He also wants to immediately repeal dozens of President Obama’s antibusiness executive orders. A pro-growth energy policy. Mr. Trump wants to employ all of America’s abundant resources—oil, natural gas and coal. His plan could make America the world’s No. 1 energy producer within five years, producing millions of new jobs and trillions of dollars of extra output—along with new royalty payments to the government. Mrs. Clinton, by contrast, brags that she would put “a lot of coal miners” out of work.We don’t see eye to eye with Mr. Trump on everything. In our opinion, legal immigrants are an asset to the country. We believe that deporting 11 million people is unworkable, and we hope in the end Mr. Trump comes to this same conclusion. Deportation should be pursued only when an illegal immigrant has committed a felony or become a “public charge.”But the difference here is smaller than often portrayed. Although Mr. Trump is depicted as a close-the-doors nativist, he has said that he favors legal immigration, and he has hired thousands of legal immigrants. His proposals on illegal immigration—to build a wall, increase enforcement of the law, deport criminal aliens, defund sanctuary cities, and reduce visa overstays—are reasonable and sensible given that voters demand action.We are also free traders and oppose punitive tariffs. The US needs trade. Yet it also must have a president willing to negotiate from a position of strength with countries that manipulate their currencies, steal Americans’ intellectual property, or compel companies to disclose trade secrets as a condition of entering their markets. Negotiating better trade deals and enforcing the current ones would help the US economy.Ideological purists miss a practical point.?Right or wrong, working-class Americans believe that they disproportionately bear the burdens of free-trade deals. Taking a tougher stance might be necessary to restore dwindling support for open markets.Concern that Mr. Trump is a showman, temperamentally unsuited for the Oval Office, is misplaced. Running a successful business enterprise as CEO is an excellent qualification for the presidency. Mr. Trump has had prolonged success. He didn’t fake that. We find it refreshing and uplifting that middle-class and working-class voters don’t envy Mr. Trump or view him as an evil rich guy. Rather, they admire his success and want to emulate it.Trump’s detractors love to point to his businesses that did not succeed. But one of the great things about the US is that people can rise above their failures. Henry Ford and Steve Jobs did, and they changed the world. The skyscrapers that bear his name all over the world are evidence that Mr. Trump has maintained a level of success that few people ever achieve.