American liberals and libertarians rarely see eye to eye - but they have united behind demands for more transparency following the revelations of vast and secretive US surveillance.
The unlikely alliance has brought together the Democratic Party's far left and the ultraconservative Republican "tea party", both of which are suspicious of the surveillance programmes, which US officials insist are needed to prevent terror attacks.
During hearings last week with the directors of the National Security Agency and the Federal Bureau of Investigation, both sides took to task their parties' congressional leaders, who had long known about the spying programmes.
"The mere fact that some members may have been briefed in a classified setting does not indicate our approval or support of these programmes," said John Conyers, one of the most liberal Democrats in the House of Representatives. "It's not a partisan concern and it is one that applies both to the present administration and to the last one, as well. It's my fear that we are on the verge of becoming a surveillance state, collecting billions of electronic records on law-abiding Americans every single day."
The hearings came after government contractor Edward Snowden leaked details of a programme to mine telephone logs and another that acquired data from internet giants, including Apple, Google, Microsoft and Facebook.
Hours after Conyers spoke, Republican Rand Paul, a "tea party" favourite and fan of libertarian philosopher Ayn Rand, said he was filing a lawsuit against the NSA for abuse of power.
"I want to catch terrorists as much as any American," Paul said, flanked by "tea party" lawmakers and an official from the American Civil Liberties Union. "But what separates us from them is the rule of law."
George Washington University political scientist Christopher Arterton said: "This is a rather unusual alliance for sure." But "there has always been a bit of harmony between the two ends of the political spectrum about big government". He recalled that unlikely coalitions rose to oppose, in 1913, creation of the US central bank and, late in the 19th century, the gold standard.
But in today's Congress far-right and far-left lawmakers do not wield much power, and the parties' leaderships have promised a debate on the surveillance programmes - not a revolution.
Moreover, public opinion on the issue is fairly mixed. A majority of Americans disapprove of the systematic gathering of a huge trove of telephone metadata, two recent polls by Gallup and CBS show. But when asked in a way that invoked the fight against terrorism, the numbers flipped.
According to a Pew study, 56 per cent viewed it "acceptable" for the NSA to track telephone records of millions of people "to investigate terrorism".
"Americans generally disapprove, in theory, of the database collection programmes, but a majority are willing to accept it under certain circumstances in order to fight terrorism," Gallup chief editor Frank Newport said.