Now that the inevitable moment of truth has finally arrived — with Donald Trump in banana republic mode, concocting a phony national emergency, flouting the will of Congress and trampling its constitutional spending power — we will soon learn whether he has fatally infuriated the Fellowship of the Furrowed Brow.

I am referring, of course, to all those congressional Republicans who have long reacted to Trump’s demagogic lies and abuses by furrowing their brows and mouthing worthless words.

Trump’s four-alarm fakery — declaring an emergency that he admits is not an emergency — has prodded some Senate Republicans to summon their usual adjectives. Over the weekend, they deemed his action “unwise.” Confronted with Trump’s imperial move to fund a fantasy wall even after Congress explicitly refused to do so, they pronounced themselves “concerned.”

But what are they prepared to actually do? They should listen to Matt Latimer, a former George W. Bush aide and lifelong conservative, who wrote, “Shame on any ‘conservatives’ who roll their eyes, shrug their shoulders, and let him take this path…Is there anyone with the courage to stop him?”

By law, an emergency declaration can be challenged by a congressional resolution of disapproval. Nancy Pelosi’s House will pass such a measure and send it to the Senate, where, again by law, it must be brought to the floor and cannot be filibustered into oblivion. Which means that the Fellowship of the Furrowed Brow will soon be forced to choose fealty to His Flagrancy — or to the Founding Fathers.

“Republican legislators face a time for choosing: Support Trump or the rule of law,” is what The Bulwark, a new website founded by sane conservatives who abhor what’s happening in America, said in a weekend editorial. “Who will speak for the non-autocratic wing of the Republican party?”

Who indeed. It certainly won’t be Senate leader Mitch McConnell, the Trump toady who’s selling out the institution he professes to revere. There have been bleats of protest from Republicans who face tough re-election races in 2020, particularly in blue states where Trump’s wall fantasy is loathed (hence Susan Collins of Maine, who said Friday that Trump’s move is a “mistake”), and even some restiveness among 2020 Republicans whose seats are presumably safe (hence John Cornyn of Texas, who warned earlier this month that an emergency declaration would “divide Republicans…It strikes me as not a great strategy”).

But will congressional Republicans join forces with Democrats and stand up when the chips are down? Empty words aside, will they actually vote for a resolution of disapproval in sufficient numbers to demonstrate that they have the guts to fight for democratic norms?

Don’t hold your breath. The typical furrowed-brow Senate Republican won’t say whether he or she would vote to disapprove. Pennsylvania’s Pat Toomey said over the weekend: “I made no secret of the fact that I hoped the president would choose to avoid unilateral action and work with Congress on a legislative solution to secure the border.” Beyond that, “My staff and I are reviewing the president’s declaration and its implications very closely.”

And on “Meet the Press,” Wisconsin’s Ron Johnson did a similar dance, saying he was “concerned” about the legislation. But when asked if he will vote for a resolution of disapproval, Johnson said, “I’m going to take a look at it and I’ll decide when I actually have to vote on it.”

I know that Republicans live in terror of the vocal Trumpist minority, but such a vote should be a no-brainer. Trump didn’t campaign on stealing Congress’ constitutionally-mandated spending power or promise to build a wall by taking money that had been legally appropriated for U.S. military housing. And back in 2014, he even tweeted that “Repubs must not allow Pres Obama to subvert the Constitution of the US for his own benefit & because he is unable to negotiate w/ Congress.”

David French, a conservative attorney writing in the conservative National Review, has a message for those who are still loath to confront our true national emergency:

“Congratulations, partisans. You claim you’re saving our country. In reality, you’re wrecking our Constitution.”

Dick Polman is the national political columnist at WHYY in Philadelphia and a “Writer in Residence” at the University of Pennsylvania. Email him at dickpolman7@gmail.com.