Obama aide slams Republican proposal on Iran

The Iran nuclear talks now include letter-writing campaigns involving the White House and Congress.

White House Chief of Staff Denis McDonough sent a letter this weekend to the Republican chairman of the Senate Foreign Relations Committee, saying President Obama would veto a GOP-backed bill to give Congress an up-or-down vote on any agreement with Iran.

The proposed bill would "likely have a profoundly negative impact on the ongoing negotiations -- emboldening Iranian hard-liners, inviting a counter-productive response from the Iranian majiles; differentiating the U.S. position from our allies in negotiations; and once again calling into question our ability to negotiate this deal," McDonough wrote.

The McDonough letter comes less than a week after 47 Republicans sent a letter to the leaders of Iran, warning that Congress or a future president could change any agreement reached this year.

McDonough appeared to reference that letter in his missive to Sen. Bob Corker, R-Tenn., chairman of the Senate Foreign Relations Committee.

Wrote McDonough:

"The Administration's request to the Congress is simple: let us complete the negotiations before the Congress acts on legislation. We understand that Congress will make its own determinations about how to respond, but we do not believe that the country's interests are served by congressional attempts to weigh in prematurely on this sensitive and consequential ongoing international negotiation aimed at achieving a goal that we all share: using diplomacy to prevent Iran from developing a nuclear weapon."

Reports The Huffington Post:

"Coming just days before the March 24 deadline for a political framework for the final nuclear agreement, the Saturday night letter -- three pages, single spaced, in length -- is the latest indication of rising tensions between the White House and the Hill.

"At times assertive and, at others, combative, the letter warns Corker that his bill, which would give Congress the right to vote up or down on the final nuclear agreement, would cripple U.S. negotiators and lead Iran and international negotiating partners to question the U.S.' ability to follow through on its end of the bargain. ...

"McDonough also assures Corker that the Senate will play a role -- 'and will have to take a vote' -- in any final agreement. But that vote, he says, should come further down the line."