The story of the Donald Trump presidency ― of a politician repeatedly violating the norms of politics and basic civility, then getting away with it ― played out in vivid form within the span of one remarkable hour on Tuesday afternoon.

It started on the Senate floor, with a speech by Arizona Republican Jeff Flake. Moments after announcing to a home-state newspaper that he would not seek reelection in 2018, Flake issued a blistering condemnation of Trump’s behavior since taking office.

“We must never adjust to the present coarseness of our national dialogue with the tone set up at the top,” Flake said. “We must never regard as normal the regular and casual undermining of our democratic norms and ideals, we must never meekly accept the daily sundering of our country. The personal attacks, the threats against principles, freedoms and institution, the flagrant disregard for truth and decency.”

A sitting senator attacking a sitting president from the same party, in such sweeping terms and in the formal setting of a floor speech — it was hard to think of anything remotely like it in recent memory. But Flake was not done. Having called out the president, he proceeded to call out his fellow Republicans for failing to speak out more forcefully, all but calling them enablers. “It’s time for our complicity and accommodation to the unacceptable to end,” Flake said. “Were the shoe on the other foot, would we Republicans meekly accept such behavior? Of course we wouldn’t.”

At Tuesday's briefing, White House Press Secretary Sarah Huckabee Sanders defended President Trump by citing the poor poll numbers of his GOP critics. (Photo: SAUL LOEB via Getty Images)

Literally minutes after Flake was done, over at the White House, Press Secretary Sarah Huckabee Sanders took the podium for her semi-regular briefing with reporters. Right away she got questions about the criticisms of Trump, which had come not just from Flake but also from Sen. Bob Corker (R-Tenn.), who has also criticized Trump since announcing he won’t be seeking reelection.

Relative to Flake, Corker has focused less on Trump’s civility and more on his basic fitness for office, wondering aloud whether the president will start World War III and calling the White House an adult day care center. Like Flake, Corker has attacked Trump as a serial liar. “The president has great difficulty with the truth,” Corker deadpanned this morning.

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Sanders responded, though she didn’t bother to refute the two senior and well-respected senators directly. She didn’t claim that the president was actually more honest, less crass or better qualified to be president than Corker or Flake had suggested. Instead, Sanders pointed out several times that Corker and Flake had terrible poll numbers, suggesting they had lost the faith of their own supporters.

“I think that the people both in Tennessee and Arizona supported this president,” Sanders said. “And I don’t think that the numbers are in the favor of either of those two senators in their states.”

It was “probably a good move” that Flake decided not to run again, Sanders said at another point, offering only a slightly nicer version of what Trump had tweeted about Corker earlier in the day, when the president said Corker “couldn’t get elected dog catcher.”

This is pretty much how the past year has gone. In Trumpland, political might makes right.

Over and over again, Trump has told blatant, easily refutable lies about everything from health care policy to his ties with Russia. He has mused openly about nuclear first strikes, attacked Gold Star families and shown a shocking contempt for democratic norms ― attacking the media, the FBI and the courts. He did it during the campaign, in the period before his inauguration and since then during his presidency.

And Trump has never stopped, because the consequences for his indiscretions have never been severe enough. Trump’s behavior didn’t cost him the presidential election and, at least so far, it hasn’t cost him the loyalty of his party in Congress, either. Plenty of Republicans say privately what Corker and Flake say publicly. But GOP members of Congress continue to support him almost without exception. More importantly, they continue to take actions that help him politically ― whether it’s by burying investigations of his potential misconduct or voting in ways that advance his priorities.

At this point, the most predictable part of any outrageous act or statement by Trump is the ensuing press conference by House Speaker Paul Ryan (R-Wis.), in which the speaker will dismiss whatever Trump has said or done with a joke ― or by pretending not to have heard about it ― and then shift the conversation to the importance of some legislative priority. In fact, it happened that way on Tuesday, after Trump’s latest Twitter attack on Corker. “I know Bob, who supported the budget, wants to get tax reform,” Ryan said, “and I know the president wants to get tax reform.”

House Speaker Paul Ryan (R-Wis.) has perfected the art of managing not to notice what Trump has said or done. (Photo: Chip Somodevilla via Getty Images)

That may be the explanation for GOP behavior right there: that Republicans are so committed to their agenda that they will tolerate a potentially unstable and dangerous president in order to enact it. Or Republicans may simply fear the wrath of Trump, figuring they are one errant tweet away from facing primary challengers who, with the help of former White House chief strategist Steve Bannon, will end their political careers.

That’s undoubtedly a big part of the story with both Corker and Flake. Both were looking at serious primary challenges from the Breitbart wing of the Republican Party. And both stood a good chance of losing, according to the polls, just as Huckabee Sanders said. If their prospects of reelection were stronger, they might not be committing such heresies now (although Flake, to his credit, has been speaking out for a while).

Still, Republicans in Congress have the power to make a difference if they choose to. It’s happened before, most memorably on repeal of “Obamacare,” when three Republican senators voted against a bill Trump desperately wanted to pass.

There will be more such opportunities in the future. Dissident Republicans could vote against the Republican tax cut, which will almost certainly violate repeated GOP pledges not to raise the deficit. They could insist upon disclosure of Trump’s tax returns or more aggressive investigations of Trump’s Russia connections. And in the Senate, where the GOP has only a 52-seat majority, a handful could even form an independent block that would remain committed to their conservative principles but operate as a check on Trump’s power. It would take only three to make a difference, though it’s easy to think of a half-dozen who would be obvious candidates to join.

The possibility of an independent GOP caucus hasn’t gotten serious attention, but Republicans truly worried about Trump would be foolish not to think about it. Trump isn’t going to change his behavior until somebody makes him. And at least for now, that somebody would have to be the Republicans in Congress.

Tuesday’s statements by Corker and Flake are a meaningful start, regardless of what steps they have or haven’t taken before. But to really have an impact, they will have to do more than give speeches. They will have to cast votes that live up to their rhetoric. And they will need some of their colleagues to do the same.

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This article originally appeared on HuffPost.