From The Times:

“I think he’s shooting himself in the foot by demonstrating a lack of real fidelity to the rule of law,” said Paul Rosenzweig, a senior fellow at the R Street think tank and a former official in the George W Bush administration. “It gives more ammunition to his opponents, and provides more fodder for investigations by the House Democrats when they come in next year.”

It was Trump’s decision to fire James Comey as FBI director in May last year that sparked the Mueller investigation. This latest move could have further blow- back. “Whether this is constitutional or not is an open and difficult question,” said Rosenzweig. “But when the presi- dent acts in a way like this, he generates unanticipated consequences that have clearly rebounded to his detriment in the past, and are likely to in the future.”