WASHINGTON- President Donald Trump would be prevented from launching a nuclear strike if a measure introduced Thursday by a group of Democrats becomes law, challenging the president to use diplomacy first.

The legislation would prevent the president from spending money for combat or any similar military action against North Korea and would bar him, and any other U.S. president, from attacking North Korea unless it strikes first.

In September Trump threatened to “totally destroy” North Korea and called Kim Jong-un “Rocket Man;” Kim responded by calling Trump a “mentally deranged U.S. dotard.”

Sen. Chris Murphy, D-Conn., said he introduced the bill to help ease tensions and maintain a diplomatic approach to North Korea. An identical bill was introduced in the House by Rep. John Conyers, D-Mich.

“I think it’s time that we started taking President Trump seriously when he talks about attacking North Korea,” said Murphy “Repeatedly he has displayed an unthinkable enthusiasm for military action on the Korean peninsula.”

Norm Ornstein, a political scholar at the conservative American Enterprise Institute, said that it is unlikely that Republicans will support the measure because they will “reject anything pushed by Democrats,” and the potential of Republicans having their “fingerprint on something that could go very badly.”

Murphy, who is a member on the Committee on Foreign Relations, pressed Defense Secretary James Mattis and Secretary of State Rex Tillerson during a committee hearing Monday on whether they believe the president has broad authority to launch a strike on North Korea. Both said the idea of an imminent nuclear threat from North Korea was too hypothetical to answer.

“The president does not have the power to engage in preemptive war without a vote by Congress,” Murphy said. “If [Trump] wants a military path with North Korea, he cannot do it without congressional authorization, and that authorization would be hard to get because the American people don’t want war.”

The Senate bill has eight co-sponsors, including Sens. Bernie Sanders, I-Vt., and Tammy Duckworth, an Iraq war veteran who represents Illinois

Trump’s tweeting “puts us on a dangerous path,” Duckworth said.

“I have become increasingly alarmed by the drumbeats of war that are growing louder in the White House,” she said. “I was personally opposed to the war in Iraq, but I volunteered to join my unit when we deployed, and I am proud of my service there, but we cannot make the same reckless march towards war in North Korea as we did in Iraq.”

Trump will embark on a 12-day, five-country trip to Asia on Friday. He will not visit the demilitarized zone on the border of North Korea and South Korea because of time constraints, a White House spokesman said. Instead, he will visit Camp Humphreys, a military installation south of Seoul, South Korea.