How much does a president need to know to lead effectively? Can a president simply rely upon experts to guide him in policy development, navigating the broader contours of leadership and performing ceremonial functions while negating the need to delve into details?

These questions are hardly new, but have received much attention of late. Republican presidential front-runner Donald Trump has repeatedly responded to criticism of his lack of policy knowledge by saying he will rely upon the best experts to guide him. The implication is that the president really doesn’t need to know much, as long as he provides a sense of direction in policy and inspires others to follow him. Trump vaguely promises to “make America great again,” and clearly a President Trump would rely upon people he hires to fill in the details.

We’ve been here before, and the hazards are real. Trump’s slogan and outsider status remind some, in a very general sense, of the political appeal of Ronald Reagan in the 1970s and the 1980 election. Reagan frequently was criticized for a lack of knowledge of policy specifics. “Reagan’s Reign of Error” was a popular book at the time, detailing his various misstatements, including that nuclear missiles launched from a submarine can be recalled. But many observers concluded that President Reagan could lead effectively with a dedicated staff and a strong cast of experts surrounding him.

His predecessor Jimmy Carter had taken much criticism for actually knowing too much about policy — he was a micromanager and an engineer-president, many said, who failed to understand that a president doesn’t need to know policy, he just needs to provide confident leadership and use the experts around him. Reagan, political observers concluded, had the right formula of providing inspiring leadership while delegating the details of policymaking and implementation to others.

But all of that changed with the Reagan Administration’s Iran-Contra scandal – a colossal leadership failure caused exactly by presidential delegating to others and not paying attention himself. White House aides carried out illicit weapons and hostage deals, nearly costing Reagan his presidency. Those individuals directly controlled the selling of arms, negotiating of hostage deals and the funneling of money to the Nicaraguan Contras. Reagan apologized to the nation for this failure — in doing so he claimed that he had known none of what had been going on in his own administration.

That scandal highlighted the difference between White House aides who merely advise presidents, and staffers who take on operational duties with no outside accountability. The fact is that a President Trump — or any of the presidential candidates once elected — can select the individuals he believes are the best experts to provide advice. As long as those White House appointees provide advice and assist the president in the formation of policy they would not run afoul of constitutional restrictions. Such individuals do not make final decisions, but merely advise; therefore they are in a support role to presidents.

But there is now a category of White House aides who have taken on operational duties such as overseeing the implementation of policy; coordinating programs among multiple departments or agencies; controlling appropriated funds; and regulating industries. These officials, unconfirmed by the Senate and nowhere anticipated in our constitutional structure, have become known as presidential “czars.” These aides seem especially suited to a future Trump Administration, where the president seeks to avoid restrictions imposed on him by separated powers and can rely on his own experts to further policy aims while evading Congress. This is a serious constitutional danger that has received little attention in this campaign.

Certainly government officials oversee the implementation of policy, coordinate programs, spend funds, and exercise regulatory controls, but those powers come with built in checks, especially the requirement that these officials be subject to Senate confirmation. Presidential advisors and other government officials become dangerous when they exercise unchecked and unaccountable powers that isolate them from legislative oversight and controls.

This danger is not new. In 2008, presidential candidate Barack Obama criticized President George W. Bush for centralizing more and more power within the White House, relying on czars and circumventing Congress. Obama claimed he would reverse that trend, but instead continued to act unilaterally on many fronts, including the increased use of presidential czars. A Trump presidency would exacerbate, not reverse, this trend.

We risk much if we elect a president who exhibits impatience with the pace of government and is dismissive and ignorant of basic government operations. Unfortunately, the public has expressed little concern about what presidential candidates know about policy and government operations.

Special To The Washington Post · Mark J. Rozell, Mitchel A. Sollenberger