Republican lawmakers are pushing three measures to roll back a nuclear agreement with Iran, while the Obama administration’s lead negotiator for the accord defended its implementation one year after the deal was struck. Three bills dealing with the agreement, under which Iran agreed to curtail its nuclear program in return for an easing of economic sanctions, are scheduled for a vote this week in the House of Representatives, where Republicans have a majority. The measures would then go to the Senate, which may not take them up before September. One of the proposals would impose new sanctions on Iran over any sponsorship of terrorism or human rights violations. Another would bar the purchase from the Islamic Republic of “heavy water,” a non-radioactive byproduct of both the manufacturing of nuclear weapons and nuclear energy. The third would block Iran’s access to the U.S. financial system, including the use of the dollar. All three measures have been met with promises of a veto from the White House. Without the Iranian accord, “we would have been forced to confront the reality of how to address Iran’s nuclear program in a world where diplomacy had failed,” Stephen Mull, the State Department’s lead coordinator for Iran nuclear implementation, said Tuesday at a Bipartisan Policy Center conference in Washington. ‘No Better Deal’ “There was no better deal to be had,” Mull said. “If Iran continues to meet its obligation and we walk away, we walk away alone. ” While the U.S. remains concerned about Iran’s missile program, support for terrorism and human rights violations, within the confines of the nuclear agreement, “this deal is working,” Mull added. After a decade of isolation under U.S.-led international sanctions, Iran is now seeing greater interest from businesses and banks in its $370 billion economy. However, Iranian officials complain that six months after the economic sanctions were eased, the country has yet to witness the financial benefits many predicted. Remaining U.S. sanctions as well as the threat sanctions could be reimposed, have kept many foreign companies away, according to Iran. Mull cited Iran’s weaknesses in transparency, banking and corporate governance. “Iran has a lot of homework to do,” Mull said. The three bills expected to be voted on this week in the House are in addition to a measure introduced to derail Boeing Co.’s agreement last month to provide 109 aircraft to Iran’s national airline, a deal valued at more than $17.6 billion. That would be the biggest business transaction between the two countries since the 1979 Islamic Revolution and the U.S. hostage crisis. In issuing its veto threat this week, the White House emphasized that the legislation would undermine the viability of the nuclear agreement. The deal “is critical to ensuring that Iran’s nuclear program is and will remain exclusively peaceful, which is profoundly in the national security interest of the U.S. and the international community,” according to the statement.