The Obama administration has defied the Republican-led US House of Representatives, invoking a claim of executive privilege as it refused to turn over documents related to a Mexican gun-running operation.
Wednesday's move prompted the House Oversight and Government Operations Committee to go ahead with plans to vote on charging Eric Holder, US attorney general, with contempt of congress.
The exchange set up yet another constitutional confrontation - the supreme court battle over healthcare and immigration being the others - between Republicans and the White House.
The Fast and Furious operation was meant to help federal law enforcement agents follow the flow of guns from Arizona into Mexico, where they were thought to fall into the hands of violent Mexican drug cartels.
But US agents lost track of many of those weapons, which later were involved in crimes, including the shooting death of Brian Terry, a US Border Patrol agent.
Fast and Furious ran from late 2009 until early 2011.
Word of the botched operation prompted the US congress to investigate the Obama administration's handling of it.
Historically, congress has had considerable difficulty enforcing contempt citations and has ultimately relied on
negotiated settlements following protracted litigation to get the information it has sought.
The Democratic president and congressional Republicans have battled since January, 2011, over everything from budget and tax policy to healthcare, immigration and keeping basic government services running.
Tensions between President Barack Obama and Republicans in congress are expected to only worsen as the November 6 presidential and congressional elections come closer.
More broadly, the dispute is one of dozens over the past half century between the congress and the White House, pitting
congress's investigative authority against the president's privilege to protect internal communications.
An administration official noted that George W Bush asserted executive privilege six times while Bill Clinton asserted it 14 times to protect documents.
Many of the struggles have wound up in the federal courts. Others have led to negotiated agreements.
One of the problems congress faces in these situations is the unwillingness of the justice department to let its
prosecutors enforce contempt citations against the executive branch, forcing congress itself to bring suit in the courts on its own.
"This is all show," Stanley Brand, former House general counsel, said.
"There's no way to enforce these subpoenas. I know the press likes to say, 'Contempt. Contempt.' The fact is that in the last 35 years, no department of justice will prosecute an executive branch official under the contempt statute, period."
He noted that when a Democratic congress tried to pursue contempt charges against Bush administration, the House had to file a civil lawsuit that "that took 2-plus years of litigation and they settled it. The chest beating about contempt is silly, because everyone knows it's not going to get enforced".
Holder has argued that over the past few months the justice department has largely co-operated with congress by turning over a substantial number of documents to the Republican-led House Oversight and Government Reform Committee.
Darrell Issa, committee chairman, has countered that the Obama administration has been slow to respond to a committee subpoena and has withheld important documents.
"I write now to inform you that the president has asserted executive privilege over relevant ... documents," James Cole, deputy attorney general, wrote to the committee.
Executive privilege allows the White House to argue that some private communications between the president and members of his administration cannot be divulged to congress.
Holder, in a letter to Obama, set out familiar legal arguments in support of the executive privilege claim.
"I am very concerned," he wrote, "that the compelled production to congress of internal executive branch documents generated in the course of the deliberative process ... would have significant damaging consequences" that would "inhibit the candour" of White House deliberations now and in the future.
If the House panel votes to charge Holder with contempt, it would then be up to the full House to decide whether to bring that charge against the nation's top law enforcement officer.
The process could take months or even years of court battles and further poison the political atmosphere in a presidential election year.