Washington (CNN) Republicans might be resorting a lot more often to prayer -- the new strategy several senators have adopted for dealing with their capricious President -- because of the forces unleashed by the latest fraught moment of the Trump era.

Senate Majority Leader Mitch McConnell did manage to avert the political disaster of a new government shutdown by securing a pledge Thursday that President Donald Trump will sign a federal funding bill that lacks money for his wall.

But he may be paying the price for years to come.

That's because the President's response to a futile effort to squeeze lawmakers for wall funding is to obliterate a constitutional guardrail in a way that could fundamentally alter the power balance between the presidency and Congress.

declaration of a national emergency to bypass Congress and reprogram funds already allocated by lawmakers would represent Trump's most striking assault yet on the system of constitutional order that he is sworn to preserve, protect and defend.

If the move is not permanently blocked by the courts it could also come back to haunt Republicans, since it could provide a precedent for a future Democratic president to enact liberal priorities on an executive whim.

"I know the Republicans have some unease about it, no matter what they say," House Speaker Nancy Pelosi said Thursday, taunting the GOP with a possible move by a future Democratic commander in chief on gun control.

"If the President can declare an emergency on something that he has created as an emergency, an illusion that he wants to convey, just think of what a president with different values can present to the American people," she added.

Thursday's drama included a painful concession for McConnell, who was forced to back off his previous opposition to declaring a national emergency in order to get Trump to sign the funding bill.

"He has indicated he is prepared to sign the bill. He will also be issuing a national emergency declaration at the same time," the Kentucky Republican said. "I've indicated to him that I'm going to support the national emergency declaration."

McConnell's institutional concerns are also likely matched with an acknowledgment that the President's coming power grab is unpopular among a majority of Americans. About 66% of Americans said in a CNN/SSRS poll released earlier this month that Trump should not declare a national emergency to build the wall. And only 64% of Republicans thought the President should go ahead -- a figure far lower than Trump's approval numbers with GOP voters.

Uncomfortable moment

Trump's move, a political maneuver that he believes will help him keep his central campaign promise and insulate his standing with his base, is likely to soon present politically dicey challenges for his fellow Republicans.

Pelosi is likely to invoke a clause in the 1976 National Emergencies Act that permits Congress to seek to terminate a President's declaration that McConnell appears to have no power to stop from coming to the floor in the Senate.

That will jam Republicans worried about the implications of presidential overreach but who will face a tough decision on whether to oppose Trump on the wall -- an issue that has an almost mystical hold on the GOP base.

It will represent yet another uncomfortable moment for a party that has often had to pick between its traditional conservative principles and standing with the barnstorming force -- Trump -- that has taken it over.

Usually, when it has been a dilemma between wielding or maintaining power and guarding principles by reining in Trump, the party has taken the first option.

A GOP senator who will face that choice again is John Cornyn of Texas, who told CNN this month that it was a "serious constitutional question" whether presidents can "usurp" the separation of powers and unilaterally dole out money.

Sen. Rand Paul, a Kentucky Republican who is sometimes a Trump ally, expressed deep reservations about the idea of an emergency declaration.

"I, too, want stronger border security, including a wall in some areas," Paul tweeted. "But how we do things matters. Over 1,000 pages dropped in the middle of the night and extraconstitutional executive actions are wrong, no matter which party does them."

I, too, want stronger border security, including a wall in some areas. But how we do things matters. Over 1,000 pages dropped in the middle of the night and extraconstitutional executive actions are wrong, no matter which party does them. — Senator Rand Paul (@RandPaul) February 14, 2019

But not every Republican has constitutional anxiety. South Carolina's Sen. Lindsey Graham has been urging Trump to declare a national emergency for days. And Louisiana's Sen. John Kennedy dismissed the fears of some of his colleagues.

"I don't join with my colleagues in believing that if the President does this, when he does it, that it will be the end of Western order," Kennedy said.

Thursday's Senate vote to avoid a government shutdown ended a difficult two months for GOP members that saw Trump walk away from a stopgap bill to avert what became the longest government shutdown in history in December.

As speculation rose that the President might refuse to sign the bipartisan agreement reached between the House and the Senate, the strain began to tell on some GOP lawmakers.

"Let's all pray that the President will have wisdom to sign the bill so the government doesn't shut down," said Sen. Chuck Grassley of Iowa.

"I pray" Trump signs the bill, said Sen. Richard Shelby of Alabama, the top Republican on the conference committee that negotiated the compromise.

Their resort to the divine summed up the grueling experience of the shutdown drama, which for all Trump's efforts to present it as a victory has left the Republican Party in a worse position than before it started.

In the end, the President got a lesson in the new dynamics of shared power in Washington that can be encapsulated by the Rolling Stones song that plays at the end of his campaign rallies: "You can't always get what you want."

The Democratic capture of the House last year made it impossible to get Congress to fund the wall -- although the President did not have much more luck when the Republicans held the chamber up until January.

He will now seek to get what he wants through an aggressive claim to presidential power that will certainly face a judicial battle that seems to have every chance of rising all the way to the Supreme Court.

'Gross' abuse of power

JUST WATCHED McConnell: Trump to sign bill, declare national emergency Replay More Videos ... MUST WATCH McConnell: Trump to sign bill, declare national emergency 00:42

Trump's critics are warning that America's constitutional architecture is now in peril from a President who has never shown much interest in submitting to institutional checks on his power.

"Just because the President didn't get what he wanted -- a stupid wall to placate his rally-goers and his right-wing media chorus -- does not mean he alone can do whatever he wants," said Frank Sharry, executive director of America's Voice, a pro-immigration overhaul advocacy group. "This is about more than a political tactic. It's an attack on our democracy by an autocrat."

Pelosi and Senate Minority Leader Chuck Schumer said in a joint statement that declaring a national emergency would be a "lawless act, a gross abuse of the power of the presidency."

"The Congress will defend our constitutional authorities," they said.

But none of that is likely to matter to the President.

This showdown has demonstrated yet again that his own political interests come before any respect for constitutional norms or an awareness of how his actions will affect the political system itself when he has left office.

If that is painful for his own side -- in this case, Senate Republicans -- Trump seems not to care. The most attractive feature of a declaration of national emergency is that it allows him to escape a humiliating set of defeats in Washington and initiative a new controversy.

Even if the courts and Democrats in the Senate succeed in curtailing his behavior, the President can rail against their efforts in order to stir his political base as he embarks on his 2020 re-election race.

That will make clear what has always been the case -- Trump cares most about his base, and rarely dwells on who or what is caught in the crossfire.