WASHINGTON — Michael D. Cohen’s congressional testimony on Wednesday revived questions about whether President Trump broke the law by failing to disclose that he footed the bill for a hush payment to a pornographic film actress.

Members of the House Oversight and Reform Committee grilled Mr. Cohen, who served for a decade as the president’s so-called fixer, about a $130,000 payment he made just before the 2016 presidential election to the actress to keep her quiet about her claim that she had an affair with Mr. Trump.

Mr. Cohen testified that he was reimbursed in installments by Mr. Trump and his company, the Trump Organization, starting in early 2017 for the payment to the actress, Stormy Daniels.

But Mr. Trump failed to list the arrangement or the outstanding debt owed to Mr. Cohen on a financial disclosure statement submitted in June 2017 under government ethics laws requiring top federal officials to divulge detailed information about their finances. On his 2018 form, he included a footnote listing a repayment of $100,001 to $250,000 to Mr. Cohen, raising questions about whether the 2017 filing had improperly omitted the debt. Democrats pounced on that omission on Wednesday.