No, you don’t have to support the president’s tweet storms. But you do have to defend his policy accomplishments. If the election is only a personality contest — rather than about the president’s policies — a historic defeat awaits.

It is undoubtedly difficult to differentiate Trump policies from the Trump persona, because the Trump persona dominates news coverage. But Republican candidates for Congress have to try. Tactically, that means being laser-focused on generating local news coverage of policy accomplishments, even when the national cable news fixates on the latest Trump outrage.

And guess what? Despite breathless coverage of the daily outrage generator in the White House, the economy is improving. The tax cuts will, and in fact already are, spurring growth, freeing capital for investment, creating jobs and returning overseas profits to our shores. There is a message to sell. So sell it.

I would go further and argue that it is the Trump persona so vilified in the media that has in fact made bolder, more sweeping reforms possible than would have been conceivable under almost any other Republican who might have been elected.

Would a President Jeb Bush have signed a strong executive order on religious liberty, or would a President Marco Rubio have started construction of a wall? Would President John Kasich have had the intestinal fortitude to execute such a huge reorganization of the Environmental Protection Agency, dismantling the liberal bureaucracy that with its deeply embedded biases harms our economy? Would President Mitt Romney have pushed through such a major tax overhaul? No way. What makes Mr. Trump different is that he just doesn’t care what the bed-wetting caucus says about his policies.

Instead of wringing our hands about his tweets, let’s start playing up his triumphs. That is the best way to minimize midterm damage. Democrats lost over 1,000 seats nationwide under Mr. Obama. While effective in engineering his own political fate, he gutted the hopes of Democrats for a decade. Republicans have to learn to do what Democrats failed to do: run campaigns as the governing party.

Half the consulting class on our side has spent half of their careers, if not more, running opposition campaigns. They have had the tailwind of resentment and grievance fueling popular anger. Now they have to flip the script. They have to learn to highlight accomplishments like tax reform, job creation and regulatory relief.

The Republican Party will either rally around its Republican president — and defend our shared accomplishments — or it will enter the fall with a depressed base and a turnout disadvantage that will lead to major losses in Congress, governorships and state legislatures. Manageable losses or catastrophic defeat: What will it be, my fellow Republicans? My answer: Fix bayonets and charge the hill.