On the eve of his criminal trial, Donald Trump told reporters in Florida that he would take the stand and testify if necessary. “All I can do is tell the truth,” Trump proclaimed.

That boast is about to be put to the test, as Trump and his defense team decide in the coming days whether to present him as a witness.

But among legal experts and even Trump’s political allies, there’s already a unanimous verdict: He would be a fool to testify.

His Republican backers say the New York trial is a sham and prosecutors haven’t proven their case — so why bother? Former prosecutors say he would open himself up to all sorts of damaging questions, from whether he had sex with porn star Stormy Daniels to alleged fraudulent business practices and inquiries about his honesty that could be political and legal landmines.