Trump's intel officials refused to promise they'd seek congressional approval to assassinate the Ayatollah: Mike Lee
Iran's supreme leader Ayatollah Ali Khamenei had vowed "severe revenge" for a US drone strike that killed storied Iranian military commander Qasem Soleimani near Baghdad airport last week. (AFP)

Sen. Mike Lee (R-UT), a staunch conservative and usual ally of President Donald Trump, has attracted national attention for blasting the classified intelligence briefing given by the Trump administration, calling it the "worst" briefing he had ever seen, saying the intervention in Iran is "un-American, it's unconstitutional, and it's wrong," and vowing to back a Democratic bill to strengthen the War Powers Resolution.

On Thursday, Lee sat for an interview with NPR, during which he revealed more details about the briefing.

According to Greg Sargent of the Washington Post, one point of the briefing that most alarmed Lee was that Trump administration officials refused to commit to seeking congressional approval if the president decided to order the assassination of the Iranian Supreme Leader, Ayatollah Ali Khamenei.

Khamenei is the most powerful and revered official in Iran, outranking even the president. A direct assassination plot against him by the United States would be an unprecedented move in modern history, and a blatant act of war that would raise serious constitutional issues about the separation of powers.

While Lee and Sen. Rand Paul (R-KY), both of whom have displayed paleoconservative, isolationist streaks, expressed their alarm about the briefing, there was little pushback from elsewhere in the Republican Party, with most GOP lawmakers, including Sen. Marco Rubio (R-FL), reporting they were satisfied by the Trump administration's argument for the strike against Iranian general Qassim Suleimani.