MSNBC’s “Hardball” host Chris Matthews wonder “whether it’s even legal or diplomatically acceptable” for Florida Senator and Republican presidential candidate Marco Rubio to say the Iran deal could be revoked on Thursday.

Matthews said, after playing a clip of Rubio saying the deal could be revoked by the next administration, that Rubio’s rhetoric is “almost a Logan Act violation to me.” He later stated, “You know I wonder whether it’s even legal or diplomatically acceptable, yes or no, for somebody running for president, who has a shot at the presidency — basically writing foreign policy, to undermine the current president, who’s the only president we have.”

Senator Ben Cardin (D-MD) argued, “It was very similar to what Senator [Tom] Cotton (R-AR) did in his letter signed by most of the members of the Republican caucus, when he told the Supreme Leader, ‘Disregard what the president of the United States is doing.’ It is over the edge. It should have no place in American politics.”

Matthews added, “I think people should remember when they observe the Constitution, and their oath of office that they should remember that all laws coming from that Constitution, and the Logan Act is one of those laws, you’re not supposed to negotiate for the United States unless you are, in fact, the United States government. ”

(h/t Newsbusters)

Follow Ian Hanchett on Twitter @IanHanchett