I’m proud to have founded the Democrats for Trump movement in 2016. President Trump’s pro-growth policies have revived the stagnating U.S. economy, and he deserves a second term. But to have the best chance of re-election, he should replace Vice President Mike Pence on the ticket with Nikki Haley.

I mean no disrespect for Mr. Pence, who’s loyally served the president and the nation. But he’s given Mr. Trump all the help he can. He inspired his fellow evangelical Christians to take a chance in 2016. But in 2020 they’ll already...