WASHINGTON -- Opponents of the Iran nuclear accord may not be able to kill the agreement in the US Congress now that 34 senators— enough to uphold a presidential veto— have come out in support of it.But a successful resolution disapproving the deal will send a clear message to the world: America, on a bipartisan basis, has severe doubts concerning the agreement going forward.That is the argument the American Israel Public Affairs Committee, or AIPAC, is making to members of Congress still on the fence. They hope a congressional vote of disapproval will convince businesses and banks seeking to quickly invest in Iran to think twice."Today, a bipartisan majority of the American people join the bipartisan congressional majority that will soon vote to reject this deal– while many of the deal’s proponents have expressed severe concerns," Marshall Wittmann, spokesperson for AIPAC, told The Jerusalem Post on Wednesday. "We believe that this strong opposition conveys an important message to the world– especially foreign banks, businesses and governments– about the severe doubts in America concerning Iran’s willingness to meet its commitments and the long-term viability of this agreement," he added.AIPAC's decision to push forward came after the Obama administration secured on Wednesday the support of a 34th senator, Senator Barbara Mikulski, Democrat from Maryland, ahead of a vote expected later this month.Mikulski's decision followed endorsements from two Democratic colleagues, senators Chris Coons of Delaware and Bob Casey, Jr. from Pennsylvania, the previous day. US President Barack Obama only needs one third of one house of Congress to ensure passage of the accord— the minimum necessary to uphold a presidential veto. Congress may still vote and pass a resolution disapproving of the deal when it reconvenes next week.The fight ahead will be over whether that vote of disapproval takes place at all. For the tally to proceed, 60 members of the Senate will have to agree to proceed with debate. Opponents of the deal are four votes shy of that number, with only 56 members publicly opposed. AIPAC said it would be fighting for an up-or-down vote - a vote supported by Senator Coons, he said on Wednesday morning, among other members of the Democratic caucus."On an issue of this significance to the national security of the United States, the American people deserve a direct up or down vote on the agreement," Wittmann said. "Preventing that vote would be contrary to the spirit of the Corker-Cardin legislation that was passed by a near unanimous margin by the Senate."