“Who should President Trump choose for V.P.?” is one of the most popular questions among the political cognoscenti right now. It’s understandable: Donald Trump won both Iowa and New Hampshire with more than 50 percent of the vote, after his closest competitors spent sick amounts of time and money trying to persuade voters to “move on” from him. Polling in Nevada, South Carolina and other upcoming primary and caucus states suggests that Mr. Trump remains in a solid position and that there is little to no “math path” for the remaining Republican competitor, his former ambassador to the United Nations Nikki Haley.

Electability is edging close to inevitability. His dominance in the polls and at the polls this year make clear the will of the people: They want Mr. Trump to be No. 1. Hence the curiosity: Who does Mr. Trump want to be his No. 2?

I am an admittedly well-intentioned but disastrous matchmaker, but I got one right when in May 2016 I recommended the then-Indiana governor, Mike Pence, as a solid running mate to Mr. Trump. As governor, Mr. Pence had cut taxes and regulations, expanded charter schools and school choice, went to Japan to seek investments in Indiana and created an innovative workaround of Obamacare through the Healthy Indiana Plan. As a congressman representing Indiana, Mr. Pence had worked in Washington for 12 years, but never became Washington. I thought he could only help us bust through Hillary Clinton’s “blue wall” in the upper Midwest and the Rust Belt and allay misgivings among evangelicals and constitutional conservatives trying to make sense of a Manhattan billionaire real estate legend and television star as the standard-bearer for a pro-life, limited-government movement.

Now, as the predictable auditions and adulations by the “pick me!” V.P. suitors begin, the list of possibilities has ballooned. Talk has turned to whether Mr. Trump should choose an insider or an outsider, a man or a woman, a legislator or an executive. Yet I think the most important vice-presidential selection question for Mr. Trump is less “who?” than “why?” In other words, the individual should complement, not complicate, his America First record and vision, and recognize the difference between loyalty-as-tenacity (yes) and loyalty-as-obsequiousness (no).

Politics is the art of addition, not subtraction — let alone distraction. A qualified running mate who attracts rather than alienates core constituencies, is ready to lead on Day 1, and who can find his or her way in front of a TV camera without becoming the headline is preferred.

Mr. Trump’s V.P. should help him win and help him govern. With a crisis on the border, economic dissatisfaction, fears about crime, a parents’ rights renaissance and multiple wars and threats across the globe, Mr. Trump’s deputy must be able to navigate chaos and challenges at home and abroad. Potential options include Mr. Trump’s former secretary of state and C.I.A. director Mike Pompeo, with whom Mr. Trump worked very well; Senator Tom Cotton of Arkansas, who serves on the Armed Services Committee; and Senator Marco Rubio of Florida, the vice chairman of the Select Committee on Intelligence and the senior Republican on the Foreign Relations Committee. Each man would seamlessly execute Mr. Trump’s America First foreign policy of no new wars and peace through strength and convey a “ready on Day 1” assurance in what is an increasingly dangerous, fraught and uncertain world. A lack of gravitas and a paucity of confidence in her competence has led President Biden’s vice president, Kamala Harris, to become among the least popular in history.