President Trump’s job approval rating remained stable amid criminal convictions and guilty pleas by two former advisers last week, new polling by The Wall Street Journal and NBC News has found.

Mr. Trump’s performance in office was approved by 44% of registered voters in a survey taken after Paul Manafort, the president’s former campaign chairman, was convicted on fraud charges and Michael Cohen, his former lawyer, pleaded guilty to tax fraud and campaign finance violations.

That...