After a summer of mass shootings, Democrats in Congress were pushing for gun reform. But now that the possible impeachment of President Donald Trump is sucking up most of the political oxygen, the window for action on guns seems to have closed.

Even if Democrats retake the White House next year, a Republican Senate would likely block new gun laws. With that in mind, a majority of Democratic candidates have indicated they would wield the power of the executive branch to reduce the number of Americans killed by guns each year.

A review of campaign platforms, public statements, and past actions suggests that 11 of the 19 remaining candidates for the Democratic Party’s 2020 presidential nomination support using executive authority to enact stronger gun policy without Congress. The proposed actions range from tweaks of the background check system to massive expansions of gun dealer licensing.

The candidates’ enthusiasm for executive action on guns demonstrates how much the Democratic Party has shed its timidity on guns, according to Adam Winkler, a professor of constitutional law at the University of California, Los Angeles, and the author of Gunfight: The Battle Over the Right to Bear Arms in America. “For years, Democrats didn’t talk about gun control and now we have very substantive platforms.”

Winkler added that while “most of the particular [executive actions] proposed are minor” compared to the bills put forth by congressional Democrats “they become significant in their quantity.”

How much power does the president actually have over gun policy?

When it comes to changing laws, not much. However, as the head of the executive branch, the president can direct how its agencies enforce gun laws and influence internal practices.

If the president wants to take unilateral action on guns, he or she can mostly act through the Department of Justice and its agencies, said attorney Lindsay Nichols of Giffords, the gun violence prevention organization. In particular, that means the Federal Bureau of Investigation, which handles background checks, and the Bureau of Alcohol, Tobacco, Firearms and Explosives, which regulates the gun industry and enforces federal firearms law. The president can prioritize enforcement of current laws, direct existing infrastructure like the background check system to operate differently, or, most dramatically, promulgate formal rule changes to rewrite the particulars of regulation. Outside of the DOJ, the president can also address the proliferation of guns through trade policy.

With that said, the president depends on Congress to fund agencies like the DOJ, which can limit the executive branch’s ability to pursue new initiatives.

How have past presidents used executive action on guns?

After Congress failed to pass gun legislation following the mass shooting at Sandy Hook Elementary School in 2012, President Obama unveiled a series of executive actions on gun policy. He unveiled another series of executive actions on guns following the 2015 San Bernardino shooting. The most significant of those directives required that the Social Security Administration turn over records of people adjudicated mentally ill to the federal background check system, and directed the ATF to more aggressively enforce a law requiring people who are “engaged in the business” of selling firearms to conduct background checks.

However, the impact of the Obama administration’s actions was negligible, according to experts, gun sellers, and federal authorities. Just a month after the actions were announced, the ATF told The Trace that Obama’s actions would not change how it regulated gun dealers, and it undertook no new enforcement efforts. Gun show organizers called the rules meaningless. And a recent analysis by The Trace found no increase in federal charges for dealing guns without a license. “Most of Obama’s actions just re-stated existing law,” said George Mocsary, a law professor at the University of Wyoming and the author of Firearms Law and the Second Amendment: Regulations, Rights and Policy.

President Trump has also used executive action to change gun policy. He had the ATF ban bump stocks through regulation, resulting in the surrender and destruction of thousands of the devices. He also reversed Obama’s effort to enter Social Security records into the background check system, and had the Department of Justice issue guidance that reduced the number of people who qualify as a “fugitive from justice” for the purposes of background checks, which resulted in fewer people with open arrest warrants being blocked from buying a gun. Trump has also said he wants to shift oversight of gun exports from the State Department to the Department of Commerce, which would make it easier to sell guns overseas, though he has not yet actually implemented the policy, which may be overturned by Congress.

What do the 2020 Democratic candidates want to do?

The 11 Democratic presidential candidates who have endorsed executive action on guns have put forth proposals that vary in specificity and ambition.

Julian Castro, Beto O’Rourke, Kamala Harris, and Elizabeth Warren have the boldest plans. They have each promised to enact a far more expansive definition of who is “engaged in the business” of selling guns than was attempted by Obama. It would likely require thousands of private sellers to get licenses and conduct checks — or stop selling guns. All four say they would reverse the Trump administration decision to use a much more limited definition of “fugitives from justice” for the purposes of the federal background check system. And they intend to use the president’s authority over trade policy to limit the import and export of guns, which they argue has worsened violence both at home and abroad.

The proposals by Castro, O’Rourke, Harris, and Warren are far more significant and wide-ranging than those pursued by past Democratic administrations, said Winkler, the constitutional law professor. “These make the executive orders from the Obama administration seem pretty small,” he said.

The remaining candidates have made more modest or vague promises. Amy Klobuchar and Marianne Williamson say they would restore Obama’s order to include Social Security records in the background check system. Michael Bennet, Cory Booker, Pete Buttigieg, and Bernie Sanders have not said which executive actions they would take, only that they would use the power of the presidency to institute gun policy.

Joe Biden has said he would use executive action to block the importation of assault weapons. As vice president, his office was in charge of the Obama administration’s efforts to limit gun violence through executive action.

What are the limits on executive action?

Executive actions aren’t always effective; whatever was done by one president can be easily undone by the next. But when Congress doesn’t act on an issue, executive actions are understandably attractive. They are also a controversial tactic, since they sidestep the legislative branch.

Even some of the candidates have questioned whether the most ambitious gun-related proposals exceed the power of the office. At the third Democratic presidential primary debate on September 12, a question on this issue drew Harris and Biden into a tense exchange. Biden insisted that the president’s executive authorities were limited when it came to cracking down on assault weapons by executive order, “Some things you can [do by executive order]. Many things you can’t,” Biden said. Harris responded by playing off Biden’s close embrace of the Obama legacy, when she joked, “Hey, Joe, instead of saying no, let’s say, ‘Yes, we can!’”

Conservative pro-gun scholars in particular dispute the idea that the president has much sole authority over gun policy. “Article 1 of the Constitution puts the power of lawmaking in Congress,” said Dave Kopel, an attorney and prominent writer on gun politics and jurisprudence. While some parts of the executive branch like the ATF may change regulations from time to time, Kopel said, ”when you have a policy or regulation that has existed for decades and you change that, sometimes courts allow that, but not always.”

Mocsary, the University of Wyoming law professor, felt that many of the Democrats’ proposals would spur opposition in courts and through the formal rule-making process. “The most significant thing the president can do is influence the ATF, and the ATF has to abide by what Congress has told it to do,” Mocsary said.

Winkler and Nichols agreed that no matter how ambitious a president may be, they can’t enact a gun safety agenda by fiat. As expansive as the proposals from the 2020 candidates may be compared to actions taken by Obama, they don’t approach what is within Congress’ authority. Winkler noted that: “The president can’t establish universal background checks by executive order. A ban on the import of assault weapons is not the same as an assault weapons ban.”