A federal appeals court in Washington expressed skepticism Tuesday about the Trump administration’s claim that Congress can never go to court to enforce its oversight and spending powers in a pair of historic disputes between House Democrats and the president.

The full U.S. Court of Appeals for the D.C. Circuit was considering two separation-of-powers cases over a House subpoena for former White House counsel Donald McGahn and its power to limit federal government spending on the president’s signature southern border wall project.

Throughout the three-hour teleconference argument, judges raised concerns about whether cutting off the courts to Congress would remove any incentive for future presidents to cooperate or negotiate with lawmakers trying to check executive power.

Justice Department attorney Hashim Mooppan urged the judges to stay out of “this political tug-of-war” that he said “risks damaging public confidence in the impartiality” of the court. A decision in the House’s favor, he said, would open the floodgates, allowing lawmakers to “come in and sue every time the executive branch exceeded its authority.”

Several judges suggested there were no limits to the Trump administration’s argument. If a president abused his powers, Judge Judith W. Rogers asked, does the Justice Department’s position mean “there’s nothing that can be done until the next presidential election other than revolution?”

In a series of hypothetical questions, Judge Merrick B. Garland asked whether the Justice Department’s view meant that presidents were free to fund the Affordable Care Act or send stimulus checks to all Americans without congressional approval.

“If the appropriations power can never be checked in a situation where the government just gives money away either for health care or for maintenance, that’s a significant power that the president has that can’t be checked by Congress,” Garland said.

House General Counsel Douglas Letter asked the judges not to “close the courtroom doors” to lawmakers who are trying to preserve their constitutional oversight and spending authority and to “help prevent the executive from becoming a monarch.”

Underscoring the significance of the cases, the court was sitting with a complement of nine judges instead of the usual three-judge panel. The consolidated arguments were held by teleconference as the court’s doors have been largely closed to the public since mid-March because of the novel coronavirus pandemic.

The full appeals court agreed last month to reconsider the dismissal of the two lawsuits brought by House Democrats, marking a temporary victory for House Speaker Nancy Pelosi (D-Calif.). The decisions will probably be appealed to the Supreme Court.

Judges Gregory Katsas and Neomi Rao did not participate Tuesday. Both were nominated by the president and previously held high-level positions in the Trump administration.

In the first case, a divided three-judge panel of the appeals court in February said it had no authority to resolve a “bitter political showdown” over the House Judiciary Committee’s subpoena for testimony from McGahn.

In a court filing this month, House lawyers said McGahn’s testimony is still relevant to ongoing oversight. His testimony will help the Judiciary Committee decide whether Trump “committed impeachable offenses” in former special counsel Robert S. Mueller III’s investigation and “whether to recommend new articles of impeachment.”

The lawsuit was filed before the House opened impeachment proceedings and voted in December to impeach Trump for his alleged effort to pressure Ukraine to conduct investigations that would benefit his reelection campaign. The Senate voted to acquit Trump on Feb. 5.

Trump had blocked McGahn’s testimony, saying the key presidential adviser was “absolutely immune from compelled congressional testimony” and could not be forced to answer questions or turn over documents.

Mooppan, representing the Trump administration, said Tuesday that lawmakers can use other political tools to compel the White House to cooperate. But several judges took issue with alternatives such as a federal government shutdown, impeachment or sending the House sergeant at arms to arrest a noncompliant executive official.

“Does it matter at all how proportionate and practicable those available remedies are?” Judge Cornelia T.L. Pillard asked. She questioned whether the House should have to resort to “huge, blunt, disproportionate nuclear options” to exercise its oversight.

In the second case, the court is considering whether the House has legal grounds to sue the Trump administration over the diversion of billions of dollars to build a border wall near Mexico.

The dispute over border wall spending between Congress and the administration prompted the longest government shutdown in history. The stalemate ended in 2019 with Congress allocating about $1.4 billion for enhanced security along the border in Texas, far less than the $5.7 billion Trump had requested.

The House lawsuit claims Trump violated the Constitution by ignoring the spending limits imposed by Congress and diverting more than $6 billion allocated for other purposes to fund the wall. He invoked statutes he said allowed him to repurpose appropriations — a move House Democrats say upended Congress’s essential check on the president and its power of the purse.

The House position attracted support from a long list of former lawyers for past House speakers from both parties and from a bipartisan group of more than 100 former members of Congress.

Justice Department lawyers told the appeals court Tuesday a single chamber of Congress cannot sue the administration because the power to appropriate federal funds is assigned to Congress as a whole.

Judge Thomas B. Griffith appeared to embrace that argument, asking the House lawyer: “Isn’t it pretty clear that you need to have the Senate with you right now to bring this suit?”

In June, a District Court judge also sided with the Justice Department and dismissed the House lawsuit.