Opinion writer
U.S. Department of the Treasury Internal Revenue Service 1040 Individual Income Tax forms for the 2011 tax year are arranged for a photograph in Tiskilwa, Illinois, U.S., on Wednesday, April 4, 2012. Automatic six-month extensions for filing tax returns are available to taxpayers using the Free File link on IRS.gov, the Internal Revenue Service (IRS) said April 3. Photographer: Daniel Acker/Bloomberg (Daniel Acker/Bloomberg)

Donald Trump must believe that whatever is in his tax returns is more damaging than the decision not to release them after promising to do so. Hillary Clinton’s campaign is trying to get him to rethink that judgment — or simply make his already miserable campaign even more miserable. Her latest ad does the trick:

Trump’s refusal underscores ongoing concerns about him: his trustworthiness (he promised to release them), lies about his wealth, his lack of generosity, and the potential for shady deals with Russians or others not friendly to the United States. And through all this, Trump remains in control of his business. There is no sign of a blind trust in the works. We don’t suspect he’d be much concerned with corruption and self-dealing.

The decision of Trump’s VP pick, Indiana Gov. Mike Pence, to release his own tax returns only highlights Trump’s refusal. Clinton campaign operatives were anxious to point that out, sending around a clip of Pence trying to deflect questions about Trump’s broken promise:

While he looks awkwardly deceptive, Pence is undeserving of our sympathy. He signed up for this and now is forced to make excuses for his boss’s inexcusable behavior. Someone should ask Pence: Isn’t he concerned about what’s in Trump’s returns?

Add the tax return outrage to the list of egregious errors made by the Republican National Committee. When it had the leverage to demand that Trump produce his taxes (by rule of the convention, for example), it didn’t use it. Now Pence, the RNC and other Republicans are stuck explaining why it’s acceptable for a billionaire to boast about paying as little in taxes as possible, a billionaire whose boasts about charitable deductions have been debunked. The media shouldn’t let up; in each and every interview, the candidates should be pressed to answer questions about this. Otherwise, no presidential candidate will ever release his or her taxes.