US President Donald Trump holds a coronavirus response meeting with New Jersey Governor Phil Murphy in the Oval Office at the White House in Washington, DC, April 30, 2020. Photo: Reuters / Carlos Barria.

Nearly 90% of US House of Representatives members have signed a letter urging the Trump administration to change the way it is dealing with the United Nations as it pushes the Security Council to extend an arms embargo on Iran, congressional sources said on Thursday.

In a rare show of bipartisanship, at least 382 of the 429 members of the Democratic-controlled House — Democrats and Republicans — have signed the letter to Secretary of State Mike Pompeo urging him to work with US allies and partners to extend the embargo, which expires in October, as well as UN travel restrictions on Iranians involved with arms proliferation.

“The UN arms embargo is set to expire in October, and we are concerned that the ban’s expiration will lead to more states buying and selling weapons to and from Iran,” said the letter, seen by Reuters and led by Representatives Eliot Engel, chairman of the House Foreign Affairs Committee, and Mike McCaul, the committee’s ranking Republican.

Congressional aides said signatures were still being collected, and it had not yet been sent to the State Department.

President Donald Trump’s administration has been taking a much harder line with the United Nations over its desire to extend and strengthen the embargo, threatening to trigger a return of all UN sanctions on Iran as leverage to get backing from the 15-member Security Council. Diplomats said that tactic would lead to a tough, messy battle.

Washington has shared its strategy with Britain, France and Germany, which are council members and parties to the 2015 deal between Iran and world powers that prevents Tehran from developing nuclear weapons in exchange for sanctions relief.

Trump withdrew the United States from that deal in 2018, promising he would make a much better one than the pact agreed upon by his predecessor, Democratic President Barack Obama.

That new and better deal has not yet materialized.

Trump’s administration has pursued a “maximum pressure” campaign seeking to limit Tehran’s weapons programs and influence across the Middle East, breaking with allies that have urged that sanctions be eased and economic aid allowed to help deal with the coronavirus pandemic.

“Maybe this can be the beginning of that better deal,” a congressional aide said.

Authors of the letter hoped it would be a return to bipartisanship on US dealings with Iran, after years of steep divisions between the two parties beginning with Obama’s work on the landmark nuclear pact.