The White House on Wednesday rejected another round of document requests from the House, expanding on its assertions that Democrats in Congress lacked a legitimate legislative purpose for the demands and were inappropriately replicating the work of the special counsel.

The letter from the White House counsel, Pat Cipollone, laid out a series of arguments, saying essentially that Congress was not a law enforcement body and does not have the standing to investigate the president.

The letter stopped short of asserting executive privilege over the documents, which relate to 81 individuals and entities connected to the president or his campaign and inauguration. The documents are being sought by the House Judiciary Committee for its investigation into possible obstruction of justice, abuse of power and corruption. But the letter framed the requests as overly broad. And it suggested that the committee was trying to get another crack at material the special counsel, Robert S. Mueller III, had already reviewed at great length.

“Congressional investigations are intended to obtain information to aid in evaluating potential legislation, not to harass political opponents or to pursue an unauthorized ‘do-over’ of exhaustive law enforcement investigations conducted by the Department of Justice,” Mr. Cipollone wrote in the 12-page letter, which was first reported by ABC News.