OPINION — In theory (and the emphasis here is on the word “theory”), the lame-duck session of Congress after a cataclysmic midterm election should be a fruitful time for bipartisanship.

With nearly 90 members of the House and eight senators not returning for the 116th Congress, old rigidities might give way to last-gasp attempts at legislating. The nothing-left-to-lose freedom of the defeated was best expressed by Mia Love, who said at her concession news conference, “Now, I am unleashed, I am untethered and I am unshackled, and I can say exactly what’s on my mind.”

But unshackling GOP legislators from Donald Trump is a lock trick that would have baffled Houdini.

Most Senate Republicans won’t face the voters until at least 2022, when Trump will be either in eclipse (the fate of most two-term presidents in their sixth year) or out of office. The 2018 rout of suburban House Republicans should remind surviving GOP incumbents that the Trump touch only works in primaries — and can be fatal in November.

But the electoral rebuke of a sitting president whose average approval rating is only in the low 40s seems to have had the longevity on Capitol Hill of a Trump tweet. Despite occasional brief bursts of independence, it is hard to find evidence that congressional Republicans feel chastened by the midterm verdict.

Paul Ryan — whose final days as speaker seem devoted to farewell addresses and victory laps — bragged at a Wednesday press conference that House Republicans have provided the $5 billion that Trump craves for his border wall. “The House is there,” he said proudly. “We just hope the Senate comes with us.”

Trump, in an interview with Politico, threatened once again to shut the government down if he doesn’t get his ransom of $5 billion (presumably in small, unmarked bills) for building a physical border wall. Once the Republicans were defined by Ronald Reagan’s “shining city upon a hill.” Now Trump’s GOP is obsessed with a phantom wall.

All the king’s horses and all the king’s men

The election should have taught Trump that applause lines at rallies do not provide a window into popular opinion. A mid-October CBS News Poll found that 60 percent of Americans oppose the wall. But like an aging standup comedian too lazy to rewrite his original jokes, Trump insisted in the Politico interview that “politically speaking, that issue is a total winner.”

True, some Senate Republicans have been humming “Don’t Fence Me In” when it comes to fully funding the new border barrier. Richard Shelby, the chairman of the Appropriations Committee, on Wednesday floated the notion of either a continuing resolution to delay the issue until next October or splitting Trump’s dreamscape of $5 billion over two years.

But Shelby’s optimistic scenarios did not factor in the loyalty of many Republicans to Trump’s outlandish fantasies about a border wall so high that even Paul Bunyan couldn’t step across it. If Trump insists on playing Humpty Dumpty with a veto next month over his wall, many Republicans will be eager to go splat with him.

In normal times, the grisly murder of Jamal Khashoggi, an American resident, inside the Saudi consulate in Istanbul and the continuing brutal war and humanitarian disaster in Yemen would provoke a strong and united moral response from America. But Trump, who wildly exaggerates the cash value of Saudi arms deals, is motivated by only a single abstract principle: money.

Jared Kushner, Trump’s son-in-law and would-be modern-day Metternich, quickly became entranced with the young and brutal Saudi strongman, Crown Prince Mohammed bin Salman. The result: The administration, including Defense Secretary James Mattis and Secretary of State Mike Pompeo, are publicly clinging to the fantasy that overzealous subordinates — and not the crown prince — were responsible for Khashoggi’s murder.

(Washington Post columnist David Ignatius, a long-time Middle Eastern expert and a personal friend, has written the most convincing account of the reckless rule of the crown prince.)

Wednesday’s peace mission to Capitol Hill by Mattis and Pompeo failed to convince wavering senators to oppose legislative efforts to punish the Saudis. The 63-37 vote to move forward with a resolution rebuking the Saudis was a rare assertion that Congress has an important voice in foreign policy. Clearly, the Trump administration erred in not allowing CIA director Gina Haspel to brief senators on the agency’s solid assessment that the crown prince was directly implicated in the Khashoggi’s slaying.

Barely a blip

Nothing about Trump’s mastery of foreign policy should invite the confidence of either hawks or doves. His fan-boy devotion to Vladimir Putin and his contempt for NATO allies defies any coherent ideology. The president’s airy dismissal of the CIA assessment as just “feelings” (as if the spy agency were a lounge singer replaying 1970s hits) is a reminder of the president’s failure to understand the rudiments of intelligence in all its aspects.

Defending this see-no-evil approach to the Saudis, Pompeo lamented in Wednesday’s Wall Street Journal, “The October murder of Saudi national James Khashoggi in Turkey has heightened the Capitol Hill caterwauling and media pile-on.”

In truth, while the Senate may still attempt to punish the Saudis during the lame-duck session, the odds of any sanctions sticking remain low. The loyalty of House Republicans to Trumpism ensures that any Senate vote will be symbolic at best.

By January, when the Democrats take control of the House, the murder of Khashoggi will have become the Capitol Hill equivalent of “old news.” The sad reality is that ultimately the potent combination of Saudi lobbying and a cynical administration are likely to derail any meaningful sanctions against the out-of-control crown prince.

So the nation stumbles on — governing by continuing resolution, routinely running trillion-dollar deficits and abandoning all moral principles in foreign policy — like a spendthrift heir trying to squander two centuries of the family fortune in four short years.