A spokeswoman for the committee’s chairman, Representative Trey Gowdy of South Carolina, said he had no immediate comment. A spokeswoman for the G.S.A. said the agency did not comment on pending litigation.
At issue is the historic Old Post Office building in Washington that the Trump Organization leased from the federal government and transformed into a luxury hotel with upscale bars and restaurants. Critics have charged that the hotel has become a conduit for foreign governments, lobbyists and other special interests seeking favor with the president to channel money to the Trump family.
But Democratic efforts to look into the hotel’s financial transactions have gone nowhere. The latest Democratic gambit hinges on an obscure 1928 law allowing members of the Oversight Committee to demand information from the executive branch without a subpoena or the support of the committee’s chairman. Known as the “Seven Member” rule, the law specifically says that any seven members of the committee, regardless of political party, can sign a request that an agency must comply with.
Lawmakers from both parties have invoked the rule in the past, although sparingly. In 1994, Republican committee members twice used it to obtain documents from the Federal Deposit Insurance Corporation and the government’s Office of Thrift Supervision.
But there are significant legal questions about whether it can be enforced in court. Henry A. Waxman, a former Democratic representative from California, twice sued the executive branch to enforce the rule when he was the committee’s top Democrat — with different results.
In the first case, a United States District Court for the Central District of California ruled in 2002 that the George W. Bush administration had to produce data related to the 2000 census requested by Oversight Committee members. The Justice Department appealed the ruling, but no resolution was reached because the data was ordered released in a separate and concurrent Freedom of Information Act case.
Mr. Waxman and fellow Democrats sued the administration again in 2006. This time, though, a different California judge found that the lawmakers did not have standing to bring the case because their suit had not been authorized by House leadership.
Mark J. Rozell, a professor at George Mason University who studies executive privilege, said he expected that standing may again be a hurdle for the lawmakers.
“It’s a difficult case,” he said. “This is a real separation of powers dilemma for the courts to try to untangle. You have a fairly obscure 1928 enactment by Congress that some court decisions have determined is not enforceable under certain circumstances.”
Democratic lawmakers will argue that they made an identical request using the rule during the final months of the Obama administration and that the G.S.A. honored the request, producing relevant documents in January.
When the members renewed their request under the rule in February, they say their letter and subsequent follow-ups were ignored by the G.S.A. In July, the agency wrote to Mr. Cummings, citing a May opinion from Justice Department’s Office of Legal Counsel that found the administration need not reply to information requests from lawmakers in the minority. Neither the letter nor the ruling mentions the “Seven Member” rule.
“There is one thing, and one thing only, that has changed in this case,” Mr. Cummings said on Thursday, according to the prepared remarks. “President Trump is now sitting in the Oval Office.”
Separation of powers cases can take years to wind through the courts, but Mr. Rozell said a ruling in the Democrats’ favor could open the door to a flood of document requests and with it a potential constitutional showdown over the executive branch’s prerogative to protect certain information.
“If they can prevail in this case, then it’s open game for these members to go after just about any and all information they want from the executive branch,” Mr. Rozell said.