Donald Trump is a weak president.

He remains a weak president after the passage of tax reform, despite what some in the media are describing as a presidential “victory.”

Granted, all presidents, including Trump, are powerful in an absolute sense; a person who can launch military strikes is not without clout. And President Trump is often assertive toward his enemies — or his allies — and talks tough about immigration and NFL players kneeling during the national anthem. But these things do not add up to a powerful presidency.

Political scientists generally measure a president’s power according to his ability to influence public policy outcomes compared to past presidents or contemporary actors, like Congress. A strong president sets the legislative agenda, passes policies reflecting his preferences, and secures bureaucratic action on his governing priorities. A weak president has difficulty achieving these things, as competing political actors impede his goals and jockey to assert their own influence.

In his classic 1960 book Presidential Power and the Modern Presidents, Richard Neustadt famously defined presidential power as “the power to persuade.” A president must convince other political actors that their own interests lie in going along with him, or at least not standing in his way, Neustadt suggested.

That definition helps to explain why the passage of tax reform is best interpreted as yet more evidence of the president’s weakness, rather than as a sudden demonstration of new stature. Trump appears to have had little influence over the timing or substance of the policies the House and Senate devised; in general, he seems content to simply sign on to whatever agenda congressional Republican leaders set. Far from unifying Republicans around a Trump agenda, he appears reduced to cheerleading for a Republican one.

The determination that Trump is a weak president, struggling to assert power — and indeed on the brink of a failed presidency — ought to be cold comfort to Democrats and liberals, because weak presidents can be dangerous leaders. While more vulnerable to electoral defeat, they may also be tempted to take risks — including foreign policy risks — to increase their stature. And that could lead to disaster.

Neustadt and presidential power

Neustadt’s key insight was that the presidency has few formal powers, and presidents consequently must bargain to secure cooperation from numerous political actors. Members of Congress have endless opportunities to support or oppose a president’s legislative program; executive branch actors can follow or ignore presidential direction; judges can rule for or against presidential positions; outside groups can support or oppose policy proposals; and the media selects issues to highlight or downplay. In every instance, these actors weigh the political costs and benefits of support and opposition.

A president’s chief resource for persuasion is his professional reputation, ideally that of a winner who achieves objectives and punishes opposition. Political actors constantly anticipate the reaction of the president (and others) to their choices. They will hesitate to oppose or ignore you if they foresee a lonely loss or fear a harsh punishment; no one in Washington sticks out a neck if it might get cut off. Conversely, support becomes elusive if there are concerns you can’t get the job done, and actors may see opportunities to assert their own power against you. Winning begets winning; losing begets losing.

Public prestige, Neustadt argued, is a related weapon in the president’s arsenal, and it operates similarly — but mediated through voters, not Washington power brokers. Political actors in a democracy are always fearful of losing public support. It can cost a public official their job, harm a judge’s prestige, or ruin an interest group. To cross a popular president risks him directing his popularity against your own. As with professional reputation, presidents who make strategic choices that enhance their prestige will find it available as a future resource.

All of this takes enormous political skill. “The presidency is no place for amateurs,” Neustadt famously wrote. Consequently, skillful management of power enhances itself. His ideal figure was FDR, a master cultivator of both professional reputation and public prestige. His foils were Truman and Eisenhower. Where FDR had an intuitive genius for wielding power and obsessive drive for amassing it, Neustadt saw Truman as insufficiently attentive to the nuances of developing sustained power. Eisenhower, Neustadt argued, came into office a public hero, but completely lacked the political acumen necessary to leverage it for influence.

For a new president, then, Neustadt lays out a road map to sustained power: demonstrate immediate competence by strategically choosing early legislative and administrative priorities to win victories and build your reputation. Accurately assess your standing to avoid early confrontations you may lose. And rapidly learn the nuances of bureaucratic power in the White House and executive branch, to master which levers to pull, when to pull them, and whom not to annoy.

A Neustadt analysis of Trump’s 2017

As Neustadt would undoubtedly note, there’s now an amateur in the White House. And through the framework he developed, Trump has had a disastrous first year. His professional reputation is awful. Major figures from his own party routinely criticize his impulsive rhetoric and chaotic management, belittle his intelligence, mock his political ideas, and bemoan his lack of policy knowledge. The White House issues talking points, and high-ranking Republicans simply ignore them. Multiple Republican-led congressional committees are investigating his administration on topics ranging from ethics violations to foreign electoral collusion.

Similarly, the president’s public prestige, measured by approval ratings, is among the worst in the polling age. He entered office with record-low approval, 45 percent, and it has steadily declined into the 30s. No other president has had an approval lower than 49 percent in December of his first year; the average is 63 percent. Such numbers sap Trump’s power to leverage popularity into persuasion. They also depress party loyalists concerned about 2018 and embolden potential primary challengers for 2020.

Some of this presidential weakness is an unavoidable byproduct of a bitter campaign and an election victory in which he lost the popular vote. But Trump has also failed to heed Neustadt’s strategic advice. He’s made simple errors that have damaged his professional reputation and public prestige — and ultimately his power.

A poor start, administrative failures

Neustadt advised presidents to choose an early agenda that would demonstrate competence. Trump’s first major policy choice was the disastrous executive order travel ban, which was poorly written, developed without consulting executive branch experts, and implemented without warning. It was ultimately withdrawn after being struck down by courts, but not before Trump fired the acting attorney general for refusing to defend it. In less than a month, Trump had demonstrated incompetence — and peeved executive, legislative, and judicial actors he’d need on his side for the rest of his term.

Since then, emboldened by those early missteps, political actors across the spectrum have defied Trump. In June, Trump sought to end the military’s policy of allowing transgender troops to serve. His initial announcement was met with unusual and blunt public pushback from the chairman of the Joint Chiefs, followed later by pushback from the secretary of defense, followed by a court striking down the order last week.

In August, business leaders abandoned Trump following his comments about a white supremacy rally, forcing him to disband advisory councils he had touted. Trump has also had contentious relationships with Cabinet secretaries and high turnover among senior White House staff. To put it mildly, Trump is widely perceived as needing significant staff management.

Legislative weakness — up to and including on tax reform

Above all, Neustadt argued, strong presidents set agendas and influence policy outcomes. In the legislative realm, Trump has done neither. Despite unified government, almost no major legislation has passed. Many observers have noted the high rates at which Republican members vote with Trump, but such stats are misleading. As with tax reform, such correlations usually involve Trump having adopted the position of the congressional Republicans, not the other way around.

What fraction of Trump’s agenda (distinct from the GOP agenda) has Congress even considered? Not a border wall or other immigration restrictions. Not major protectionist legislation. The president did submit a budget for fiscal year 2018, which was declared dead on arrival by Democrats and Republicans. It has been almost totally ignored by appropriators, just as Trump’s suggested 2017 budget numbers were. One important bill that was approved was a trade measure Trump opposed, reducing his discretion to adjust sanctions against Russia. That one passed almost unanimously.

The president’s top legislative objective — Obamacare repeal — was defeated, but not before Trump leaned on Republican representatives to support a bill that he later repudiated as “mean,” leaving those who voted for it hanging out to dry. Throughout the process, Trump announced contradictory policy positions, blindsided allies with changing tactics, and publicly bickered with key lawmakers. Having built up a reservoir of ill will with key senators, he was unable to pull the final bill across the finish line. Maybe he should have started with an infrastructure bill.

Nominations tell a similar story about a leader with little influence. It’s true no Trump nominee failed on the floor. But floor votes almost never fail; leaders don’t bring them up unless they’re confident they’ll pass. Twelve Trump nominations, however, have been withdrawn. And presidents don’t nominate people they know the Senate will never approve. That explains why Steve Bannon and Michael Flynn got White House jobs while Elaine Chao, Steve Mnuchin, and James Mattis got Senate-confirmed positions. Likewise, Trump’s nominee to chair the Federal Reserve is not a populist hero but an establishment Republican. Most of Trump’s nominees reflect GOP priorities, not the president’s campaign promises.

Trump’s scope of action has been constrained by his early missteps

Weakness is both a consequence of a president’s prior political actions and a constraint on his future options. Trump’s weakness, for example, makes it less likely he’ll fire Bob Mueller, the special counsel he loathes, and more likely he will face consequences if he does. If Trump had a strong professional reputation, a 58 percent approval rating, and had recently repealed the ACA and passed tax cuts, he might weather firing Mueller. Instead, such an action might precipitate the end of his presidency.

Recently, retiring Republican Sens. Bob Corker and Jeff Flake strongly broke with the president, saying, respectively, that he “debases our country” and is “dangerous to our democracy.” Some critics dismissed these broadsides as mere rhetoric paired with no action. This is misguided. In politics, such criticisms are actions; they signal voters looking for approval cues and elites in need of political cover. The lack of pushback against Corker and Flake from their Republican colleagues also sent a clear message: If you want to challenge the president or his agenda, we won’t come after you.

A core Neustadt principle is that the president’s formal powers are far too weak to sustain him, absent help from the other political branches — including members of his own party. And no presidency, save the utter failures of Andrew Johnson and John Tyler, has lacked co-partisan support to the degree Trump does. The Republican Party has not thrown the president overboard; their collective electoral and policy incentives do not (yet) support that. But they seem content to let him flounder.

Trump’s aggressive norm breaking has also awakened institutional patriotism across the system — including the judiciary. Trump has repeatedly ridiculed federal judges who have ruled against him, prompting then-Supreme Court nominee Justice Neil Gorsuch to publicly repudiate Trump’s criticism. With several cases regarding the government’s power over immigrant deportation and detention on the docket this term, and the third version of the travel ban back on the radar, would it be surprising if the Court sought to assert its own power?

America has invested tremendous administrative responsibility in the modern presidency. And even the best system of laws cannot function well when there is a vacuum at the top. The presidency is also uniquely positioned to handle matters of state and foreign crises; in this respect, the presidency has actually grown more powerful in the modern era. A weak and constrained president may see opportunity in risky or destructive action, at home or abroad, in an attempt to reverse his fortunes and exert authority.

Political actors on the left and right may see partisan or ideological benefits in a severely weakened Trump presidency. But while Democrats may cheer the congressional rejection of the Trump budget and the administrative incompetence that doomed the travel ban, they should be nervous — as Americans — about just how weak Trump has become. A president unable to effectively govern the bureaucracy or lead American foreign policy poses a distinctly nonpartisan problem for the nation.

Matthew Glassman is a senior fellow at Georgetown University’s Government Affairs Institute. Find him on Twitter @MattGlassman312.

The Big Idea is Vox’s home for smart discussion of the most important issues and ideas in politics, science, and culture — typically by outside contributors. If you have an idea for a piece, pitch us at thebigidea@vox.com.