The leaders of the House committee investigating the Capitol attack have grown divided over whether to make a criminal referral to the Justice Department of former President Donald J. Trump, even though they have concluded that they have enough evidence to do so, people involved in the discussions said.

The debate centers on whether making a referral — a largely symbolic act — would backfire by politically tainting the Justice Department’s expanding investigation into the Jan. 6 assault and what led up to it.

Since last summer, a team of former federal prosecutors working for the committee has focused on documenting the attack and the preceding efforts by Mr. Trump and his allies to reverse his defeat in the 2020 election. The panel plans to issue a detailed report on its findings, but in recent months it has regularly signaled that it was also weighing a criminal referral that would pressure Attorney General Merrick B. Garland to open a criminal investigation into Mr. Trump.