Sen. Tom Cotton, the junior senator from Arkansas, is in the headlines this week for a letter he penned to Iran’s leadership, saying Congress would not support any nuclear deal it found lacking. The letter was signed by 47 GOP senators and has attracted criticism from opponents who say it amounts to treason.

Cotton, 37, was took office in January, having unseated longtime Democratic Sen. Mark Pryor in last year’s mid-term elections. He previously served one term in the House, representing Arkansas’ 4th Congressional District and is currently the youngest serving senator in Washington. He studied at Harvard Law School and was a lawyer for a short time before seeking public office.

His five years of service in the U.S. Army with tours in Iraq and Afghanistan and young age have put him on the radar of political analysts, who see him becoming a strong voice in coming years for the GOP, particularly in regard to defense and foreign policy issues.

He was appointed to the Senate Committee on Armed Services shortly after taking office and will work with some of the GOP’s leading voices, including John McCain of Arizona, Ted Cruz of Texas and Jim Inhofe of Oklahoma. He is also a member of the Committee on Banking, Housing and Urban Affairs, the Select Committee on Intelligence, the Joint Economic Committee and the Special Committee on Aging.

Cotton is a strong critic of the Iranian government and argued the Republican-dominated Senate should do everything in its power to stop Iran from developing a nuclear weapon, even if that means threatening military intervention. The letter is controversial because the negotiations led by the Obama administration in Geneva between Iran and the five permanent members of the U.N. Security Council -- the United States, Britain, France, China and Russia -- plus Germany have the potential to put an end to Iran’s nuclear program and the crippling sanctions imposed by the Security Council a decade ago.

Cotton argued all he sought to do was let Iran’s leadership know any agreement that isn't approved by the Senate is merely an executive agreement and not a binding treaty. Critics, however, say the letter shows the U.S. is not united on the issue and cannot be trusted, and that could derail the talks. 

Cotton’s open letter, signed by all but seven of the 54 Republicans in the Senate, garnered much criticism from the Obama administration and Democrats and some Republicans. Vice President Joe Biden called it “beneath the dignity of an institution I revere,” but Cotton fired back, saying Biden was “wrong about nearly every foreign policy and national security decision in the last 40 years.”

“It’s more appropriate for members of the Senate to give advice to the president, to Secretary Kerry and to the negotiators,” countered Sen. Susan Collins, R-Maine, an 18-year veteran of the body, Politico reported. “I don’t think that the ayatollah is going to be particularly convinced by a letter from members of the Senate, even one signed by a number of my distinguished and high ranking colleagues.”

The letter was sharply criticized by Iranian Foreign Minister Javad Zarif, who said it had no value legally and was nothing more than a “propaganda ploy” meant to derail negotiations. Read his full response here, via Vox.

For better or for worse, the letter could become a defining move for the freshmen senator. In the letter, Cotton boasted his colleagues will still be in office long after President Obama's term expires in 2017. If the letter backfires, however, that could be wishful thinking.