WASHINGTON — Twenty-six senators introduced legislation Thursday that could raise sanctions on Iran and compel the United States to support Israel if it launches a preemptive attack on the Iranian nuclear program, defying President Obama and drawing a veto threat.
The bill, sponsored by 13 Democrats and 13 Republicans, sets sanctions that would go into effect if Tehran violates the nuclear deal it reached with world powers last month or lets the agreement expire without a long-term accord. The measures include a global boycott on Iranian oil exports within one year and the blacklisting of Iran’s mining, engineering, and construction industries.
The goal, according to supporters, is to strengthen the negotiating leverage of the Obama administration as it seeks to pressure Iran into a comprehensive agreement next year that would eliminate the risk of the Islamic republic developing nuclear weapons. But it could also add complications for US negotiators, who promised Iran no new economic sanctions for the duration of the six-month interim pact that was finalized Nov. 24 in Geneva.
‘‘Current sanctions brought Iran to the negotiating table and a credible threat of future sanctions will require Iran to cooperate and act in good faith at the negotiating table,’’ said Senator Bob Menendez, Democrat of New Jersey, who spearheaded the effort with Senator Mark Kirk, Republican of Illinois.
Kirk called the draft law ‘‘an insurance policy to defend against Iranian deception.’’
The Obama administration has furiously lobbied Congress not to impose new sanctions, even on a conditional basis, saying the increased economic pressure could force Iran to withdraw from the negotiating process and strain ties between the United States and its key negotiating partners — Britain, China, France, Germany, and Russia.
Iran’s foreign minister also has said new sanctions could scuttle hopes of a diplomatic resolution.