Washington ( CNN ) In a strongly worded letter , the White House Saturday told Senate Foreign Relations Chairman Bob Corker ( R-TN ) a bill he is drafting would likely have a `` profoundly negative impact '' on the ongoing negotiations between the U.S. and Iran over Tehran 's nuclear program . Corker is working on legislation that would force the Obama Administration to submit any deal reached with Iran for a vote by Congress . The White House earlier threatened to veto such a measure . White House Chief of Staff Denis McDonough , in the three page letter released publicly Saturday evening , told Corker his legislation could be detrimental to the talks with Iran by `` emboldening Iranian hard-liners , inviting a counter-productive response from the Iranian majiles ( Majles , the Parliament ) ; differentiating the U.S. position from our allies in the negotiations ; and once again calling into question our ability to negotiate this deal . '' As the U.S. and Iran prepare for the next round of negotiations this coming week , there has been a growing debate between Republicans on Capitol Hill and the Obama Administration about how much authority Congress has regarding the fate of the agreement . `` The legislation you have introduced in the Senate goes well beyond ensuring that Congress has a role to play in any deal with Iran . Instead , the legislation would potentially prevent any deal from succeeding by suggesting that Congress must vote to 'approve ' any deal and by removing existing sanctions waiver authorities that have already been granted to the President , '' McDonough wrote . The chief of staff said that only Congress can terminate the existing Iran sanctions that are included in laws , but the President can relax some sanctions put into place by executive order unilaterally . One of the major issues between the U.S. and Iran is the timetable for lifting of the sanctions . `` If congressional action is perceived as preventing us from reaching a deal , it will create divisions within the international community , putting at risk the very international cooperation that has been essential to our ability to pressure Iran . Put simply , it would potentially make it impossible to secure international cooperation for additional sanctions , while putting at risk the existing multilateral sanctions '' now in place , McDonough said in his letter . For his part , Corker on Sunday released a statement : `` On this issue where Congress has played such a vital role , I believe it is very important that Congress appropriately weigh in before any final agreement is implemented . '' Corker also urged the President not to go to the United Nations for a vote regarding lifting of the sanctions on Iran , as Reuters reported was being considered . `` Enabling the United Nations to consider an agreement or portions of it , while simultaneously threatening to veto legislation that would enable Congress to do the same , is a direct affront to the American people and seeks to undermine Congress ' appropriate role , '' he wrote . The chief of staff told Corker , `` The Administration 's request to the Congress is simple : let us complete the negotiations before the Congress acts on legislation '' and added `` we will aggressively seek public and congressional support for a deal -- if we reach one -- because we believe a good deal is far better than the alternatives available to the United States . '' McDonough also mentioned a separate letter sent to Iran 's leadership and signed by 47 Republican senators . Corker did not sign it . The letter maintained that a future president could reverse some of what is agreed to in these ongoing negotiations and said any agreement reached would need congressional approval . It has generated much controversy . It also drew rebuttal from Iran 's foreign minister , who called it a propaganda ploy . On Sunday , Iran 's speaker of parliament and former nuclear negotiator , Ali Larijani , said the letter signed by the senators tarnished Washington 's reputation internationally , according to state-run Tasnim news agency . He said it showed that the United States is untrustworthy , and he advised current negotiators to be wary . McDonough also said the letter 's premise was incorrect . `` Non-binding agreements -- like the deal we are negotiating with Iran ... are an essential element of international diplomacy and do not require congressional approval , '' McDonough said . Secretary of State John Kerry , who heads back to Switzerland on Sunday for more talks with Iranian representatives , again blasted that letter from the 47 Republicans . `` It is a direct interference with negotiations in the executive department , '' he said at a news conference in Egypt . `` It is completely without precedent , and it is almost inevitable it will raise questions in the minds of the folks with whom we are negotiating . ''
A Republican senator is drafting legislation to allow Congress to vote on negotiations with Tehran . The White House sent a letter saying it would further threaten talks over Iran 's nuclear program .