The department told the House Intelligence and Judiciary Committees last week that it was opposed to the testimony and had communicated its view to the two former members of Mr. Mueller’s team, Aaron Zebley and James L. Quarles III, according to a senior congressional official familiar with the discussions. A Justice Department official confirmed that account and said that the department had instructed both men not to appear.
It is unclear what effect the Justice Department’s intervention will have on the men’s eventual appearances, but it raises the prospect that a deal lawmakers thought they had struck last month for testimony from Mr. Mueller, the former special counsel, and the two prosecutors could still unravel.