For two hours last Thursday, the House held a debate that harked back to the heyday of Sonny and Cher and Butch and the Sundance Kid. Instead of lockstep polarization on Capitol Hill, throwback Thursday marked a brief return to the era when legislative coalitions crossed party lines.

The topic before the House was the intersection of civil liberties and national security — about the only issue that can still upend standard red-and-blue divisions.

More precisely, it was a fight over the reauthorization of Section 702 of the Foreign Intelligence Surveillance Act, or FISA, which allows the government, in many cases, to search without a warrant the communications of U.S. citizens with foreigners.

“There is a reason why a left-right coalition — the NAACP and FreedomWorks, the Color of Change and the Gun Owners of America — have come together,” California Democrat Zoe Lofgren said on the House floor. Lofgren, along with Michigan Republican Justin Amash, championed an amendment to dramatically expand the use of judicial warrants in Section 702 searches that sweep up emails and phone calls involving Americans.

The Amash amendment, which represented the key House vote on Section 702, failed by a vote of 183-233. But 58 conservative Republicans joined 125 liberal Democrats in bipartisan support.

Watch: Trump’s 2018 Legislative Agenda is Already Slipping

Covering his bases?

Adding to the Thursday drama were two contradictory tweets on the amendment within two hours of each other by Donald Trump, thereby demonstrating that the president’s athletic prowess is exceeded only by his mastery of legislative details.

The Senate will be debating reauthorization of Section 702 this week, with only a last-gasp filibuster threat by Republican Rand Paul and Democrat Ron Wyden standing in the way of passage. The odds are high that the chamber will invoke cloture, since Majority Leader Mitch McConnell prevailed Thursday on an initial procedural vote on the legislation by a filibuster-proof 68-27 margin.

The larger question here transcends the complex details of Section 702: What is it about civil liberties and freedom from government snooping that has the power to scramble everything we know about contemporary politics?

If there was a pattern to the House debate on FISA, it was a cleavage between the national security establishment and congressional outsiders.

Both Nancy Pelosi and Paul Ryan (“We’re making sure we have the tools in this age of 21st century terrorism to keep America safe”) spoke in favor of the bill and against the Amash amendment. So did Adam Schiff, the ranking Democrat on the House Intelligence Committee and a favorite MSNBC guest for his critical comments on the congressional Russia investigations.

On the other side were such odd-duck allies as Manhattan Democrat Jerry Nadler and right-wing Texas Republican Ted Poe. Amid charges that critics of Section 702 were emboldening terrorists, Poe responded, “We’re not talking about terrorism. We’re talking about protection of Americans and their information.”

Worth discussing

Sixteen years after 9/11, when America is still on war footing around the world, it is bracing that the word terrorism no longer halts all critical discussions of national security matters.

During the House debate, Utah Republican Chris Stewart direly warned that any challenge to reauthorizing Section 702 “would be putting troops and American lives at risk.” In years past, that might have been game, set and match. Now Stewart’s remarks were merely treated as standard-issue congressional hyperbole before a major vote.

Beyond terrorism, it is also impressive that there remains a potent left-right coalition wedded to a belief in privacy.

Assaults on the integrity of our personal information are everywhere. Facebook peddles your comments on a friend’s wedding to advertisers; your credit card files have probably been hacked; government agencies are perfecting facial recognition techniques to identify you in a crowd; and your iPhone or Android can be tracked anywhere.

Yet a stubborn faith endures in an individual’s Fourth Amendment rights against unlawful searches and seizures. It is this belief in the Constitution as written that powered the close vote in the House on the Amash amendment.

The Senate has a far more muted anti-establishment streak than the House. But interesting patterns could be detected among the 27 senators who indicated skepticism about the automatic reauthorization of Section 702.

Three Democrats facing potentially difficult 2018 re-election campaigns (Tammy Baldwin, Sherrod Brown and Jon Tester) voted “no” on the initial procedural vote. So did four others in the Democratic Conference who may be running for president in 2020 (Kirsten Gillibrand, Kamala Harris, Bernie Sanders and Elizabeth Warren).

Since the early days of the Cold War, Congress has been willing to cede to the president and the executive branch many of its traditional foreign policy and war-making powers.

The only time when the pendulum shifted the other way was during Watergate and immediately thereafter when Congress passed the War Powers Act and sponsored a major Senate investigation into CIA assassination plots and other abuses.

As Trump demonstrates his unfitness for office every day (after the past week, do you really need examples?), we are at the point when Congress should reassert itself in the area of national security.

Does it inspire confidence that a top Trump National Security Council official — according to Spencer Ackerman of The Daily Beast — once proposed withdrawing NATO troops from Eastern Europe to appease Vladimir Putin? Or that, as Gerald Seib reported in The Wall Street Journal, the Pentagon is currently debating surgical strikes on North Korea?

Soon Congress will have to decide which represents the bigger risk: continuing to give Trump free rein on national security or taking the heat for aggressively challenging a dangerously incompetent and impulsive president in an age of terrorism?