WASHINGTON -- In January, we ran an analysis that summed up how President Trump had changed public life in America. The surest thing, the headline said, was exhaustion.

Turns out, that was just a warm-up.

The explosive end of Year Two of the Trump administration has brought chaos on an entirely new level, with consequences extending beyond the daily news cycles and even America’s borders.

The president, reversing course on an apparent agreement, has blown up a bipartisan spending deal and left the government closed as his third year in office looms. With Congress having left town Saturday, parts of the federal government is set to remain shut until Thursday, at least. With a few Twitter keystrokes, Trump has altered American influence in the Middle East, vowing to pull U.S. troops out of Syria and remove a significant number from Afghanistan, massive decisions that went against the advice of his top military aides. In response, his most widely respected cabinet member, Secretary of Defense Jim Mattis resigned with a scathing letter that made clear he felt Trump was damaging alliances that had set the world order. Mattis has been seen in the U.S. and overseas as a steady counter to the president’s mood swings,

And amid the roiling atmosphere the stock market plunged -- clouding one of the bright spots that had underpinned the president’s political support. The Dow and S&P 500 were on track for their worst December since 1931.

“It is in some ways a perfectly Trumpian end to the second chaotic year of his presidency,” wrote ABC News analyst Rick Klein.

The moves have left Trump increasingly isolated, with key aides jettisoned, the House lost to Democrats, and his relationship with even loyal congressional Republicans frayed. It all comes as a raft of Democratic challengers line up to take aim at Trump in 2020, with campaign announcements likely to begin as soon as January.

“Really struggling to see how more chaos and manufactured crisis helps Trump or [Republicans],” tweeted Amy Walter, a political analyst at the nonpartisan Cook Political Report. “2018 was literally a referendum on this and [Democrats] won popular House vote by almost 9 pts (the largest margin since ‘86).”

Sen. Lindsey Graham (R., S.C.), one of Trump’s most vocal supporters, went to the Senate floor to say that the Syria decision was “a stain on the honor of the United States.” Senate Majority Leader Mitch McConnell (R., Ky.) issued a statement saying he was “particularly distressed” by Mattis' resignation.

Mattis' resignation letter was a two-page rebuke of Trump’s world view. Mattis bluntly pointed to the way Trump has placated rivals and alienated allies who had relied on the U.S. as international ballast.

“My views on treating allies with respect and also being clear-eyed about both malign actors and strategic competitors are strongly held and informed by over four decades of immersion in these issues,” Mattis wrote.

Rough translation: I know what I’m doing. You don’t.

It was all punctuated by the shutdown that took effect at midnight Friday, after Trump turned his back on a bipartisan deal that the Senate had approved by voice vote, with the understanding that the president backed it. Senators were so sure of the agreement that some had left Washington, but Trump changed course and renewed his demand for billions for his promised border wall. The shift left America looking at a Christmas shutdown, and the possibility that Year Three of the Trump administration would dawn with a shuttered government.

The brawling even overshadowed the most significant bipartisan achievement of Trump’s tenure, a landmark criminal justice reform bill that passed with a major push from the president. He signed it Friday, as the government funding fight dominated the news.

“We arrived at this moment because President Trump has been on a destructive two-week temper tantrum, demanding the American taxpayer pony up for an expensive and ineffective border wall that the president promised Mexico would pay for,” Senate Minority Leader Chuck Schumer (D., N.Y.) said on the Senate floor Saturday.

Republicans, despite controlling both chambers of Congress, effectively threw up their hands. McConnell said it was up to Trump, Schumer, and House Minority Leader Nancy Pelosi to come up with a deal.

Trump blamed Democrats, who have used their power in the Senate to block a spending bill that would put $5 billion toward a wall along the country’s southern border.

“I won an election, said to be one of the greatest of all time, based on getting out of endless & costly foreign wars & also based on Strong Borders which will keep our Country safe. We fight for the borders of other countries, but we won’t fight for the borders of our own!” Trump tweeted Saturday.

Indeed, the president promised to smash the old way of doing things, without regard for Washington’s niceties or customs. That was part of his appeal.

But at the same time, Trump also pitched himself as a deal-maker who could bend Washington to his will. This week instead saw him tear up a deal because his own will crumbled in the face of criticism from conservative television personalities.

As the shutdown neared Friday, Trump was tweeting out the equivalent of digital doodles of his wall while Vice President Pence and Trump’s son-in-law, Jared Kushner, negotiated on Capitol Hill.

“They had a deal,” U.S. Rep. Mark Sanford (R., S.C.), who has clashed with the president, told CNN Friday. “The president completely reversed himself on that deal and now he’s going off in a different direction. That kind of back and forth is at odds with the kind of stability that our country has usually stood for.”

But the president appears increasingly untethered from such values, and he has rid himself of the kind of aides, including Mattis, who might once have restrained him.

He now finds himself backed ever more into a corner, with Democrats vowing to probe his administration and special counsel Robert Mueller seeming to near a conclusion of his investigation into Russian election interference and the Trump campaign.

It all suggests that the upheaval isn’t just a story of the moment -- it appears to be a portent of things to come.