A Capitol Police car patrols the Capitol grounds at about 2 a.m. Saturday, after all business had ceased. (Michael S. Williamson/The Washington Post)

The elements that produced this weekend's government shutdown sum up the first year of Donald Trump's presidency: a dealmaking chief executive who can't make a deal; a divided Republican Party struggling to govern and in an uneasy relationship with the president; and a Democratic Party tethered to its anti-Trump progressive base in the face of political risk.

It was fitting that the anniversary of Trump's inauguration would be a day of chaos, uncertainty, recrimination and efforts at political point-scoring. That has been a hallmark of the Trump presidency. Why should the anniversary of his swearing-in be significantly different from most of the previous 365 days?

A year ago, in his inaugural address, Trump promised to bring a swift end to what he called "this American carnage." He promised disruption. At the one-year mark, the Trump era has certainly brought disruption to the capital, exposing the fault lines and vulnerabilities of the governing process. The shutdown could be short in duration — it is good for neither party, nor the president — but the climate of distrust and ill will is not going away.

In the early hours of Saturday, after the last efforts to avoid a shutdown failed and Senate Majority Leader Mitch McConnell (R-Ky.) and Senate Minority Leader Charles E. Schumer (D-N.Y.) traded accusations of blame, some scorekeepers were trying to assess the political fallout. That probably will prove a fruitless exercise.

Polls offered contradictory predictions. A new Washington Post-ABC News poll showed that 48 percent of Americans said they would blame Trump and the Republicans for the shutdown rather than Democrats, whom only 28 percent blame. A CNN poll found that by 56 to 34 percent, people said avoiding a shutdown was more important than dealing with the fate of the undocumented immigrants known as "dreamers" at this time.

History suggests caution, however, in predicting the impact. In 2011, President Barack Obama thought he could avoid the fallout when the debt ceiling negotiations with congressional Republicans imploded. He was wrong; although a shutdown was averted, everybody in Washington took a hit. Two years later, many people predicted political doom for Republicans after House hard-liners led the government into a shutdown. A year later, the GOP went on to win a handsome victory in the 2014 midterms.

So it is better to stay in the moment. Begin with the president. If he had one attribute that seemed credible as he campaigned in 2016, it was that he liked to make deals. He is a transactional being by nature, given not to political philosophy or introspection or policy smarts or deep analysis. He likes action that produces trophies.

Yet the story the past two weeks is of a president who either doesn't know his own mind, isn't in charge of his own White House or simply cannot be trusted with his word. He ping-ponged from promising to take heat if legislators brought him an immigration deal, to balking when Sens. Richard J. Durbin (D-Ill.) and Lindsey O. Graham (R-S.C.) delivered the outlines of one, to unexpectedly summoning Schumer to the White House on Friday for talks, to deciding or being persuaded by those around him not to go ahead with whatever he and Schumer were discussing.

That's the record as it appears from outside the room. The full story of what really transpired inside over those many days is still being reported and written, and there's little doubt that revisionism is taking place at a furious pace. History is written by the winners, but in this case, there are no winners. No one can claim victory when the governing process collapses as it did Friday.

But the president bears significant responsibility for the mixed signals he delivered and for not making clear his bottom line. It was telling that neither the Democrats nor Trump's Republican allies on Capitol Hill knew what he was willing to accept.

The Ohio Clock outside the Senate Chamber strikes midnight at the Capitol, signaling the beginning of the government shutdown. (Oliver Contreras/For The Washington Post)

The Republicans own the government in Washington, controlling the White House, the House and the Senate. Yet over the past year, they have found themselves repeatedly stymied by their own internal divisions, their lack of clarity on matters such as health care, and their tense relationship with a president whom few of them favored during the 2016 GOP primaries and whose behavior rankles even those who have remained relatively silent.

The Republicans have made a bargain: accept the president's bad behavior as a price for moving a conservative agenda. They've pushed through judges at a fast pace. They managed to pass a tax bill in record speed at the end of last year, an accomplishment they hope will pay dividends in an election year they head into with a certain amount of dread. But this has been anything but an enjoyable year for those who dreamed for years of having the kind of power the party now has.

Since the fall — as Republicans pushed to lower the corporate tax rate and provide income tax cuts that will greatly benefit the wealthy — two vulnerable populations awaited help.

One group is the dreamers, undocumented immigrants brought to the United States as children, who were given protected status by Obama but suddenly saw that protection taken away by Trump.

The other is the beneficiaries of one of the most popular and successful safety net programs of the modern era, the Children's Health Insurance Program, better known as CHIP.

Both these groups of young people became central players in what turned into monthly battles over funding the government for the duration of this fiscal year. That, despite the fact that an overwhelming percentage of Americans — including elected officials from both parties, as well as the president — favor extending CHIP and restoring the dreamers' protection from deportation.

Border security is one price Trump and conservatives demand for a deal to protect the dreamers — that and other changes to the immigration system. Congressional Republicans nervously watched as Schumer went into a meeting with the president with none of their party's leaders in the room, their fears eased somewhat by their confidence that White House Chief of Staff John F. Kelly would prevent the president from making a deal conservative hard-liners would reject.

Republicans attached a six-year extension of CHIP to the latest short-term spending bill, hoping the move would force Democrats to swallow the bill without a deal on the dreamers. That calculation, cynical in the eyes of Democrats — who have been calling for action on CHIP for months — failed and created the conditions that helped bring about the shutdown.

Democrats, meanwhile, showed how a year of grass-roots resistance to Trump has affected their party. The party not only leans further to the left; it is also more militant in opposition to the president, making any negotiation complicated. The power of this resistance blossomed the day after Trump's inauguration with the Women's March, nationwide outpourings that were larger and stronger than anyone anticipated. Women continue to lead the resistance to Trump, and Saturday's anniversary marches across the country highlighted that anew.

Meanwhile, on Capitol Hill, daily demonstrations by dreamers and their allies have heightened the pressure on Schumer and other Democratic leaders not to let another opportunity pass to fix their status. They urged party elected officials to stand firm, using this short-term spending bill as leverage, although the ultimate Deferred Action for Childhood Arrivals deadline is in early March.

The demands of the base not to yield on immigration, however, do put red-state Senate Democrats, who face tough reelection challenges, in an untenable position. Four of them — Indiana's Joe Donnelly, Missouri's Claire McCaskill, North Dakota's Heidi Heitkamp and West Virginia's Joe Manchin III — defected on the key vote and sided with Republicans. They were joined by the chamber's newest senator, Democrat Doug Jones of Alabama.

The split between the vulnerable red-state senators and the rest of the party underscored the ideological center of gravity in the Democratic Party and the commitment to base-driven politics that party strategists see as their best path ahead.

The principal actors will find a way out of this shutdown, although any agreement could again be temporary. That will put it back on Trump's shoulders to decide what kind of deal he's prepared to make — and on Democratic leaders to choose how much to yield on border security and other presidential demands. But nothing is likely to change the underlying dynamics that created this moment. What an anniversary this turned out to be.