Reversing all of his predecessor’s gun-control policies is one of the few concrete policy pledges President-elect Donald Trump made to gun voters on the campaign trail. Fulfilling that pledge could get complicated.

Shortly before securing his party’s nomination this spring, Trump distilled his gun policy goals to a crowd of NRA members at the group’s Great American Outdoor Show.

“Every single Biden attack on gun owners and manufacturers will be terminated my very first week back in office,” Trump told the crowd.

While the promise reflects a degree of typical Trumpian hyperbole, there are a few Biden actions that Trump could derail with immediate dispatch.

The fate of the White House Office of Gun Violence Prevention is a prime example. Just this past week, the National Shooting Sports Foundation called on Trump to disband it on day one of his new term, something he could do without challenge. The office, barely a year old, was created by President Joe Biden through unilateral executive authority and could be dispensed with in the same fashion. Alternatively, Trump has plenary authority to simply re-staff the office with employees more sympathetic to gun rights than its current occupants and redirect its mission to one focused on promoting gun owners’ interests.

The same is true of the makeup of the ATF and its enforcement priorities under the current administration. President Trump could immediately fire current ATF director Steve Dettelbach, something he has previously pledged to do. Replacing him with a new permanent director of Trump’s choosing would, of course, require Senate confirmation. Still, with his party holding a three-seat majority, that should be reasonably easy to achieve–depending on how controversial the nominee is.

Even before a new permanent director is confirmed, Trump could appoint an acting director, something he had for the entirety of his first term, and influence their enforcement priorities. Under Dettelbach’s tenure and at the behest of Biden, the agency has pursued a “zero tolerance” enforcement policy against federally licensed gun dealers that has rankled the industry’s relationship with the agency as license revocations have skyrocketed. Trump could immediately order his acting director to reverse course on this inspection and revocation crackdown.

Beyond agency personnel and priorities, the road to undoing President Biden’s gun-control agenda becomes much less immediate and straightforward.

Some of Biden’s most consequential gun actions came in the form of official ATF rules, such as his ban on so-called ghost gun kits, reclassification of pistols equipped with stabilizing braces, and expansion of who must be federally licensed in order to sell used guns. Undoing these regulatory changes won’t be as simple as signing a day-one letter.

While the Trump administration has the authority to direct the ATF to rescind those rules, the process for seeing that carried out is as slow and prone to legal challenges as the initial rule rollouts themselves under the terms of the Administrative Procedures Act (APA).

“The APA’s rulemaking requirements generally apply to the repeal and amendment of rules, as well as to their initial issuance,” a 2021 report from the Congressional Research Service reads. “Thus, if an agency seeks to rescind or change an existing legislative rule, it generally must do so in compliance with the APA’s requirements, unless an exception applies.”

That means issuing a notice of a proposed rule change, giving the public an opportunity to comment on said proposed change, and then publishing a final rule to take effect a month after this process is complete. This process would also be subject to the same types of lawsuits that President Biden’s gun-control rules have drawn.

“Courts generally apply the same scrutiny to review an agency’s rescission of a rule as they do for a rule’s issuance,” the CRS report reads. “An agency must explain its departure from prior policy and show that its new policy adheres to the underlying statute; is supported by ‘good reasons’; and is better, in the agency’s belief, than the prior policy. It must also address factual findings that are inconsistent with those supporting the former rule and consider ‘serious reliance interests’ affected by a change in policy.”

While, at first glance, it may seem like a repeal effort of executive orders that have been called into question by multiple federal judges would have a stronger legal leg to stand on, this exact scenario has proven challenging for Trump before.

In his first term, the Trump administration moved to undo President Obama’s unilaterally created Deferred Action for Childhood Arrivals (DACA) program, stating it believed the program was an unlawful exercise of agency authority and that Congress would have to act if it wanted the program to continue. After drawing lawsuits, the repeal effort ultimately reached the Supreme Court, where a 5-4 majority ruled that the Trump administration’s effort was an “arbitrary and capricious” violation of the APA for failing to properly articulate a policy rationale for the change and consider the degree to which there were “legitimate reliance interests” implicated by the change.

Withstanding legal challenges could prove especially challenging for a potential repeal of President Biden’s “ghost gun” rule. That rule is currently awaiting a Supreme Court opinion, and the tenor of oral arguments suggested that a majority of the justices are leaning toward upholding the rule as a proper reading of federal firearm statutes. If so, the Court may not be willing to let the ATF undo that reading under Trump.

Finally, by far the toughest hill to climb for the Trump administration’s stated goal of repealing all of the Biden administration’s gun achievements is the Bipartisan Safer Communities Act. When President Biden signed it in 2022, it became the first federal law to prohibit new groups of people from owning guns in nearly 30 years. Doing away with it would require an act of Congress.

Though Republicans will hold majorities in both chambers of the legislature starting next year, each is likely too slim to make the passage of a repeal bill feasible. Clearing the Senate would require seven Democratic votes to thwart an inevitable filibuster effort, even assuming unanimous Republican support to take on a repeal effort, which is unlikely. After all, 14 House Republicans and 15 Senate Republicans voted to support the bill in the first place.

Still, there’s clearly plenty of low-hanging fruit for the Trump administration to reach for right out of the gate. However, gun owners shouldn’t be surprised if the new administration can’t grasp everything Biden did. Ultimately, a full-scale reversal of the Biden administration’s gun-control gains is unlikely–even if Trump can get most of the way there.