Donald Trump’s promise to overhaul both foreign and domestic policy through his leadership skills vastly overstates and misunderstands the power he would hold if elected president, according to political scientists and scholars of the presidency.

The real estate mogul has said that he would convince the Mexican government to pay for a wall along the U.S.-Mexico border, forge close ties with Russian President Vladimir Putin and stop U.S. jobs from being outsourced abroad. When asked how he will achieve these outcomes, Trump often points to his success in business, particularly his ability to negotiate.

But Trump, these scholars argue, is promoting an idea of the presidency sometimes referred to as the Green Lantern theory, named after the Green Lantern Corps, a fictional police force in DC Comics whose members wear all-powerful rings. The U.S. president, according to this theory, is often cast as a person with essentially a magic wand allowing him or her to shape outcomes.

Scholars say such a view ignores the role, incentives and power of members of Congress, the American public, private businesses and foreign governments, who can block or limit the goals of a president.

“The idea that we just need a president who will get things done is much simpler and more appealing than the complex realities of our political system,” said Brendan Nyhan, a political science professor at Dartmouth University who has written extensively about the Green Lantern idea.

“In a way, Trump’s claims about what he’ll do as president are as fantastical as those Barack Obama made during the 2008 campaign. In this case, though, the magical force is Trump’s deal-making rather than the supposed bipartisan consensus that Obama or his election would create,” Nyhan added.

Julia Azari, a Marquette University professor who has written extensively about presidential leadership, said Trump is not appreciating how hard it to change U.S. policy, even as president. She noted that President Obama has found it impossible to extricate the U.S. from conflicts in Iraq and Afghanistan started under George W. Bush, even as Obama campaigned on getting American troops out of both countries.

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“How much can one person do? There’s all the talk about going in there and changing things,” said Azari. “But reversing policy course is much harder than that. There are people invested in the status quo, getting them to do something differently takes a lot more than just bluster.”

In offering this powerful model of the presidency, Trump is rejecting the approach of Obama in the latter stages of the presidency. Obama has largely abandoned the hopes of his 2008 campaign to create bipartisanship.

Instead, the president, while a lawyer by training, often speaks in the language of political scientists, regularly noting the limits of his power to influence foreign leaders like Putin or congressional Republicans at home. He and his aides now largely reject the view that Obama could have gotten more backing for his agenda in Congress if the president had spent more time holding dinners and other meetings with Republicans in Congress.

Such a view, Obama aides argue, underestimates the political and substantive reasons Republicans oppose many of the president's proposals, no matter how hard he tries to persuade them.

Trump is not alone among the 2016 candidates in suggesting a larger and perhaps unrealistic role for a president. Vermont Sen. Bernie Sanders is promising to lead a political revolution that will bring out millions of new voters, resulting in Democrats winning control of both the House and Senate and pushing through his very liberal agenda. Jeb Bush has said his presidency will result in the U.S. economy growing by 4 percent.

Hillary Clinton has promised she would issue executive orders to implement her proposals if Republicans remain in control of the House or Senate and block them.

Scholars are very skeptical either Bush or Sanders could achieve their goals, because they are largely out of a president’s hands. And the executive orders that Clinton wants to implement could be rejected by courts, which have struck down a number of Obama’s executive actions.

“I think most if not all of the candidates exaggerate the powers of the presidency,” said John Sides, a political scientist at George Washington University. “This is certainly true for Trump. Personally, I’d like to see candidates try to educate voters about the real nature of the American system, with its separation of powers and checks and balances. But that doesn’t make for a good campaign slogan.”

Trump though may be embracing the Green Lantern idea more than any other candidate. The real estate mogul has largely downplayed policy ideas in his campaign, but the border wall is one of his biggest promises, even though it requires huge spending by the Mexican government.

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His campaign slogan theme, “Make America Great Again,” is also very broad and implies a very powerful chief executive.

“I think that I would probably get along with him very well, and I don't think you would be having the kind of problems that you're having right now,” Trump said of Putin in a recent CBS News interview.

Speaking to Bloomberg News last month, Trump repeatedly batted aside questions about whether his goals were achievable, three times using the phrase, “it’s called leadership.”

“I’ve had great success. I know how to be successful. The things I do, I’m successful at. Even when the world changes, I’ll be building a big, massive building. Everything’s fine. Then all of sudden, boom, one day there’s a depression because we’ve had depressions virtually -- I make it work,” Trump said. “I go back, I, you know, knock the banks, I do numbers, I do this, I do that, I sue, I do everything. In the end, I make it work. I always make it work. “

He added, “I will just make it happen.”

Trump’s more realistic path to influence as president is likely the traditional route: having Republican members of Congress support his agenda. In 2009 and 2010, when Democrats controlled both houses of Congress, Obama was able to push through an economic stimulus bill, a major health care reform and an overhaul of student loan policy. Much of Obama’s legislative agenda died once Republicans took over the House in 2011.

Republican leaders in Congress have been reluctant to embrace Trump. But if he were elected president and Republicans kept control of Congress, the real estate mogul would have a great ability to push through his ideas, particularly on areas like cutting taxes where Trump largely agrees with the GOP.

And Azari noted that Trump could use the presidency and his communication skills to shift the national political dialogue, even if his actual policy ideas are still not implemented.

“He put immigration front and center in the election, he set the terms of the debate,” she said. “If everyone is responding to what you’ve said, you’ve done something in politics.”