Sen. Tom Cotton (R-AR) said on Sunday cited Iran's control of their own capital, Tehran, as a reason that the country had to be stopped from obtaining a nuclear weapon.

In a interview on CBS, Face the Nation host Bob Schieffer pointed out that Cotton's letter to Iran, which was also signed by 46 other Republican senators, may have undermined President Barack Obama's ability to get a nuclear deal with Iran.

"Let's say the deal falls through, then what?" Schieffer wondered.

Cotton replied by quoting Israeli Prime Minister Benjamin Netanyahu.

"The alternative to a bad deal is a better deal," the freshman senator insisted. "The Iranians frequently bluff to walk away from the table. If they bluff this week, call their bluff. Congress stands ready to impose much more severe sanctions."

"Moreover, we have to stand up to Iran's attempts to drive for regional dominance," he continued. "They already control Tehran and, increasingly, they control Damascus and Beirut and Baghdad. And now, Sana'a as well."

"They do all that without a nuclear weapon. What they would do without a nuclear weapon."

Cotton told Schieffer that he had "no regrets at all" about sending the letter to Iran.

"If the president and secretary of state were intent on driving a hard bargain, they would be able to point to this letter and say, 'They're right -- as Secretary Kerry said on Wednesday in his Senate testimony -- any lasting deal needs to be approved by Congress.'"

"The fact that President Obama doesn't see this letter as a way to get more leverage at the negotiating table just underscores that he is not negotiating for the hardest deal possible," Cotton concluded. "He is negotiating a deal that is going to put Iran on the path to a bomb. If not today or tomorrow, then 10 years from now."