Kamala D. Harris says if Congress doesn’t impose new gun control rules in her first 100 days, she’ll do it herself. Elizabeth Warren promises to unilaterally ban drilling on public lands. Bernie Sanders tells crowds he’ll use executive action to reinstate Deferred Action for Childhood Arrivals as part of immigration reform.

Even Joe Biden and Amy Klobuchar, who are running on their ability to forge compromises with Republicans, envision single-handed presidential edicts to tackle issues including climate change and gun violence.

As the Democratic candidates offer plan after plan, many are promising single-handed presidential action — rather than new laws that must be pushed through a sluggish Congress — to combat the nation’s big problems.

That trend was particularly evident at a gun safety forum in Las Vegas Wednesday, where almost every candidate who spoke has promised some kind of executive action to bolster gun control.

“Durable reform requires legislation — but right now legislation is impossible,” Warren, a U.S. senator from Massachusetts, wrote in releasing her gun plan in August. “Why? A virulent mix of corruption and abuse of power.”

The unilateral approach in some ways echoes President Trump’s strategy, even as Democrats increasingly label him an authoritarian. The Democrats’ policies would not amplify presidential power to the extent that Trump has sought to, but they do reflect a more president-centric approach to governing, a feature that’s become central to Trump’s tenure.

While the question of presidential authority is now at center stage, the popularity of executive action in both parties began growing years ago, analysts say, driven by a growing tension between voters demanding dramatic change and a Congress increasingly paralyzed by partisanship and polarization.

The Democratic hopefuls whose message is more revolutionary — Warren, Sanders, a senator from Vermont, and perhaps Harris, a senator from California — are emphasizing executive action more than those who foresee a return to bipartisan cooperation. In some ways, the issue is drawing a line between candidates, such as former vice president Biden, who see Trump as an aberration, and those who believe the days of bipartisan comity may not return any time soon.

Some lawmakers warn that the trend could distort the balance of powers. Biden, who served in the Senate for 36 years, is among those arguing that the legislative process, cumbersome though it may be, forces the parties to work together in ways that benefit the country.

“[The Constitution] says you have to get a consensus to get anything done,” he told reporters in June. “And if you can’t get a consensus, guess what? Power flows to the president, and abuse of power takes place.”

Regarding the Democrats, he added, “The idea that we’re going to come along and do the same thing [Trump] did? Not on my watch.”

But even Biden’s platform includes promises such as “on day one, Biden will sign a series of new executive orders with unprecedented reach” to tackle climate change.

Pete Buttigieg, mayor of South Bend, Ind., made a slightly different argument against executive action at that gun control forum Wednesday when he argued that gun control is among those issues “too important to be left to the whim of an individual president.”

“Because an executive action can be reversed — and because an overwhelming majority of American people want this to get done anyway — I really feel that legislation is the best way forward,” he said.

Presidents dating to George Washington have used executive action, some to seismic effect. Franklin D. Roosevelt used his powers to implement key parts of the New Deal. Harry S. Truman’s Executive Order 9981 integrated the U.S. Armed Forces. Both had faced congressional opposition that precluded the passage of legislation to achieve their goals.

“As long as you have a divided government, you’ll have executive action,” said Elaine Kamarck, who worked in the Clinton administration and now directs the Center for Effective Public Management at the Brookings Institution. “You can think of it as poor man’s legislation.”

But in recent years, executive action has become an increasingly common substitute for legislation. Presidents often say they’re being forced to act because of Congress’s paralysis. As the Senate and House have become more polarized, they have struggled to enact major bills — prompting presidential edicts on issues such as immigration and health care.

The result can be a whiplash, where each new president enacts sweeping policies only to have them abruptly reversed when the opposition takes over. That’s been most evident in the much-reversed “global gag rule,” a provision banning foreign organizations that get U.S. aid from providing abortions or talking about them.

“A Democrat comes in and says, ‘Yes, we will give foreign aid to entities that perform abortions.’ . . . The Republicans come in and they say, ‘No, we’re not doing that,’ ” Kamarck said. “So things like abortion become like a ping-pong ball.”

The ping-pong balls will probably increase, if Democratic rhetoric on the campaign trail is any indication. In the last debate, Harris was asked about Biden’s charge that she and others were following Trump’s damaging example by promising sweeping presidential actions, some of which might not be constitutional.

Harris didn’t directly rebut the criticism. But talking to reporters at the New Hampshire Democratic Party Convention last month, she spoke of Congress’s failure to tackle “some of the longest-standing issues that are challenging our country.”

“If the United States Congress fails to act, absolutely I’m prepared to take executive action,” she said. “And that will be no different than previous presidents of the United States.”

In contrast, Montana Gov. Steve Bullock, who like Biden touts himself as a centrist who can work with Republicans, sees limits to what executive action can achieve, because by definition it shuts out the opposition.

“I think that executive orders can play a critical role,” Bullock said. “But you can’t assume you’re going to lead for four years — if you’re actually going to lead — just by executive action. . . . You’re not going to be able to substantially and sustainably move things forward if it’s just by executive order.”

Harris, saying “elections matter,” argues that immediate corrective action will be needed after Trump leaves office. Many Democrats consider the Trump presidency a crisis that requires an emergency response, and they’ve been frustrated as the president uses his powers to do things such as transfer funds to build a U.S.-Mexico border barrier or enact rules aimed at weakening the Affordable Care Act.

Harris and other candidates often say they will ask Congress to pass certain bills and will issue an executive order only if it fails to do so.

But while the candidates often talk about issuing executive actions as though it’s like waving a magic presidential wand, the reality is more complicated. For all their reach and impact, executive orders only cover the activities of the federal government and its workforce, and they can take time to implement.

Harris’s proposed order expanding background checks on gun buyers, for example, would not instantly change the system. Instead, it would direct the Bureau of Alcohol, Tobacco, Firearms and Explosives to change its interpretation of the current law requiring gun dealers to conduct background checks.

By directing ATF to classify as “dealers” even those who sell as few as five guns a year for profit, Harris would significantly expand the number of people covered. That would have a big effect — but the next GOP president could undo Harris’s action immediately upon taking office.

The fight over executive action has been brewing for some time, as each new president pushes the envelope a little further. After the 9/11 terrorist attacks, Democrats excoriated President George W. Bush for his expansion of national security powers.

Obama then issued 276 executive orders in his eight years in office. That was fewer than other recent two-term presidents, but Republicans criticized the scope of Obama’s actions, such as establishing the Deferred Action for Childhood Arrivals (DACA) program — a sweeping bid to end the deportation of those brought to the United States illegally as children.

When Trump took office, he seized on executive orders with particular gusto, staging televised signing ceremonies to suggest bold action on promises such as banning travel from some Muslim countries.

As Trump has tested the limits of presidential power, parts of his orders have been found unconstitutional, and some are still being litigated. Trump, propelled to office by voters looking to shake up the system, has issued 125 executive orders since his inauguration, according to the Federal Register.

Now it’s Democratic voters who are demanding immediate change, suggesting that for all their temporariness and shaky status, the appeal of executive actions continues to resonate with a restless electorate.

“Look at what happens in the first few weeks of the last two or three presidential administrations,” said Phillip J. Cooper, professor of public administration at Portland State University and author of “By the Order of the President.” “They walk in the door and in a period of about two months, they issue a large number of these things, to try to show their constituents that they are indeed responding to what they ran on.”