To the Editor:

Re "Why Trump Must Show His Taxes” (Op-Ed, Aug. 15):

Mark Sanford reminds us that candidates’ tax returns can reveal character by showing whether what they do matches what they say. Unfortunately, he clings to the hope that Mr. Trump will keep his promise to release his tax returns before the election. A long record of violating commitments suggests that this vow will be broken as well.

As Mitt Romney and others have said, there must be “a bombshell” in the Trump tax returns or they would have been made public long ago. Apparently Mr. Trump has been advised that while stonewalling carries risk, releasing the returns would doom the campaign by destroying his claims to success and generosity.

Apart from its probable effect on the election, he also has to know that damage to his businesses might last for years.

Mr. Sanford, like many Republicans this year, seems to be torn between party loyalty and the need to distance himself from Mr. Trump.