Now we know why President Trump picked Mick Mulvaney to fill multiple roles within his administration.

Mulvaney, who serves both as Trump's budget director and chief of staff, went on television over the weekend and defended some of the president's most recent embarrassing behavior. In doing so, Mulvaney demonstrated his utter loyalty to Trump and complete shamelessness.

It's true that Trump has a reputation for unapologetic transgressiveness. But it was once the case that administration officials could display public embarrassment of this president's antics. Those days are mostly gone — as Mulvaney's weekend performance proves — and that will have consequences for the way Trump's opponents choose to plot their path forward.

In the span of a few hours on Sunday, Mulvaney did the following:

  • Defended Trump's affinity for North Korean dictator Kim Jong Un, even after reports that some of Kim's negotiators had been executed in the wake of the failed Trump-Kim summit earlier this year

  • Professed powerlessness in the wake of the Virginia Beach mass shooting that ended in the deaths of 12 victims, plus the shooter

  • Offered tacit approval to the White House staffer who asked Navy officials to hide a destroyer named after the late Sen. John McCain during Trump's recent visit to Japan

It is incredibly shameful that the president's best working relationships always seem to be with murderous autocrats. It's embarrassing that victims of mass shootings don't get better than a shrugging "what are you going to do?" response from their president. And it's disgraceful — even authoritarian — to attempt to hide a rival's name from the president's sight. That Mulvaney would pretend otherwise is very odd.

Indeed, Mulvaney's parade of brazeness is a sign we've entered a dangerous new era in this presidency. During the first year or so after Trump took office, the White House was filled with top officials who had the good sense to occasionally appear embarrassed by their boss. Former Chief of Staff John Kelly enacted his anguish for the cameras. Gary Cohn, Trump's former chief economic adviser, publicly contemplated resignation after Charlottesville. Former Secretary of State Rex Tillerson let it be known he thought Trump was a moron.

Those officials are mostly gone, along with the sense that there are grown-ups left serving this White House. That means it's time for the president's opponents to be bolder than they have so far shown themselves to be.

Why? Because it seems Trumpism is becoming more firmly rooted in American political culture — and this development cries out for a powerful response.

There are several basic theories about the rise of Trump. One suggests that this particular moment in American politics is an aberration — that the mix of policies and pugnaciousness we loosely define as "Trumpism" will go away about the time that Trump does. This is explicitly the rationale of former Vice President Joe Biden's 2020 candidacy. "I believe history will look back on four years of this president and all he embraces as an aberrant moment in time," Biden said in announcing his run for president.

It also explains why House Speaker Nancy Pelosi (D-Calif.) keeps slow-walking impeachment, even as she continually makes the case that Trump is unfit for office: If Trump is an aberration, you don't have to be too bold in your response to him — you only have to outlast him.

That Trump's first wave of officials appeared embarrassed by his antics seemed to affirm this theory; Cabinet members displayed shame because they suspected that history would judge them. Mulvaney's performance, however, suggests that fear is dissipating, that the president's commitment to never apologizing and never admitting error — the brash, attitudinal aspect of Trumpism — is spreading beyond Trump himself and embedding itself in the GOP's broader political culture.

And so, Mulvaney appears to think he will never have to pay a price — reputationally or otherwise — for his behavior. That's a problem. If shame is eliminated from our politics and leaders avoid confrontation, there's little that can truly restrain public officials from bad acts: In addition to checks and balances, the Founders expected that a desire to avoid public embarrassment would keep America's leaders in line.

If Trumpism is more than a one-off, then the problem is urgent, and Pelosi's patience with regard to impeachment is unwarranted. It also means Biden, despite his rhetoric, won't be able to uproot the forces the president has unleashed simply by beating Trump in a single election. Mulvaney could afford to be outrageous on Sunday because he doesn't think he has to fear the future. Democrats and other Americans must be similarly fearless in deciding how to respond.