Right now, perhaps the best thing Paul and Rubio have going for them is each other. When Rubio proposes a thoughtful reform of student loans, he stretches the boundaries for Paul. When Paul says Republicans need to reach out to racial minorities — even with his own complicated history on race — or “agree to disagree” on social issues, he creates elbow room for Rubio.

But this two-man dynamic isn’t sufficient: Rubio remains battered by his attempt to solve a problem, immigration, which the base doesn’t want solved, and Paul remains too much of a party outlier. They could use a hand from a third amigo: Jeb Bush.

By entering the presidential race, Bush would be a spokesman for sane conservatism, but he would also be another force pushing against the party’s contraction. His deliberately provocative comments on immigrants — in which he described crossing the border as an “act of love” — alienates him from the rank and file. And his refusal to walk away from his support for the Common Core education reforms won’t help win those voters back. But by establishing himself as a Chamber of Commerce candidate who refuses to kowtow to the Cruz wing, he can help loosen the straitjacket that keeps Republican politics and policy so dangerously restricted.