"A number of members both on and off our committee have raised questions about the authorities of the legislative and executive branches with respect to war making, the use of nuclear weapons, and conducting foreign policy overall," Corker said in a statement Wednesday.

The announcement of the Nov.14 hearing before the Senate Foreign Relations Committee, which Corker chairs, amounts to a significant escalation of what has so far been a war of merely words between the powerful Republican and his party's standard-bearer.

After months of questioning President Donald Trump's temperament and fitness for office, Sen. Bob Corker, R-Tenn., announced Wednesday that he would convene a hearing to examine the president's authority to use nuclear weapons.

"This continues a series of hearings to examine those issues and will be the first time since 1976 that this committee or our House counterparts have looked specifically at the authority and process for using U.S. nuclear weapons. This discussion is long overdue, and we look forward to examining this critical issue," Corker said.

The announcement came less than a day after Trump delivered a combative speech aimed at North Korean leader Kim Jong-Un, in which the president called North Korea a "dark fantasy" and a "military cult." Speaking in South Korea, Trump accused the hermit kingdom of being founded on "a deranged belief in the leader's destiny to rule as parent-protector over a conquered Korean Peninsula and an enslaved Korean people."

Trump's insistence on engaging in brinkmanship with the nuclear-armed dictator has stunned many military and foreign policy professionals, who fear the president's ego could lead the country down a path to war.

Some of those professionals are scheduled to testify at Tuesday's hearing. One, Brian McKeon, is the former Acting Under Secretary for Policy at the Department of Defense under President Barack Obama, and a critic of Trump's approach to nuclear-armed North Korea.

Another witness is retired Air Force General Robert Kehler, a former commander of the U.S. Strategic Command and an expert in nuclear weapons and the capabilities of America's nuclear arsenal.

The third witness is Peter Feaver, a former director for Defense Policy and Arms Control at the National Security Council during the George W. Bush administration. In 2016, Feaver was one of nearly 50 Republican national security officials who signed a letter opposing Trump's candidacy for president. Since then, Feaver has made no secret of the fact that he views Trump as a potential threat to national security.

"In a crisis, for instance with a nuclear-armed North Korea, Trump's temperament could be problematic and could lead to dangerous escalation, whereas another President with better self-control might be able to manage it more safely," Feaver told the Duke University Chronicle in August of last year.

A White House spokesman did not immediately respond late Wednesday to a request for comment on the hearing.

Feaver's view is one that Corker has expressed repeatedly, not least when he called the White House "an adult day care center" last month in response to attacks from Trump.

Senator Bob Corker tweet: It's a shame the White House has become an adult day care center. Someone obviously missed their shift this morning.

Trump first began targeting Corker in August, after the senator criticized Trump's response to a deadly white supremacist march in Charlottesville, Va.

"The president has not yet been able to demonstrate the stability nor some of the competence that he needs to demonstrate in order to be successful," Corker told Chattanooga website Nooga.com.

The Tuesday hearing is scheduled to being shortly after 10:00 a.m. ET.