[caption id="attachment_154843" align="alignright" width="211"] Sen. Tom Cotton said he'd "welcome" presidential candidates -- including Hillary Clinton -- to sign a controversial letter to Iran .[/caption]
Washington (CNN)Sen. Tom Cotton said Tuesday he'd "welcome" presidential candidates to join the 47 Senate Republicans who signed a controversial letter to Iran warning the country's leaders that a lasting nuclear deal would have to be approved by Congress.




And Cotton said he would welcome "even Hillary Clinton," the presumptive Democratic presidential frontrunner, to join the effort.


"I suspect she might have reservations about this ill-fated nuclear deal with Iran as well," Cotton said on CNN's New Day.


Several potential GOP presidential candidates have already signed onto the letter. Sens. Ted Cruz, Marco Rubio and Lindsey Graham are among the 46 Republicans who signed onto Cotton's letter "to the Leaders of the Islamic Republic of Iran."


President Barack Obama slammed the letter on Monday, accusing the GOP of making "common cause with the hard-liners in Iran" by attempting to undercut ongoing negotiations that face a first deadline for a framework agreement at the end of the month.


Critics have accused the Senate Republican signatories of attempting to blow up delicate talks and undermining Obama's authority in an unprecedented show of partisanship on the international stage.


But Cotton said Tuesday on CNN's "New Day" he doesn't believe the letter is in any way "unprecedented."


Instead, Cotton countered that Obama's attempts to reach a nuclear accord with Iran without congressional approval would be unprecedented.


Senate Republicans, supported by a number of Democrats including Robert Menendez, introduced legislation that would give Congress a chance to weigh in on a nuclear deal. That bill's Republican sponsor, Foreign Relations Committee Chairman Sen. Bob Corker, did not sign onto Cotton's letter.


But even if that bill falters, Congress would have to pass legislation to lift economic sanctions on Iran to allow a nuclear deal to go into effect -- giving lawmakers an opportunity to weigh in then.


In the face of mounting criticism in the U.S. and abroad -- including from Vice President Joe Biden, a Senate veteran and enthusiast -- Cotton insisted that the letter was not intended as a partisan move and was instead aimed at keeping the U.S. from reaching a bad and "dangerous" deal.


"This letter is about stopping Iran from getting a nuclear deal," Cotton said. "One way that we make sure that we get a better deal is that we stand strong."


"We're not talking about just stopping Iran from getting a bomb today or tomorrow, but 15 years from now," Cotton added.


By CNN