A Republican majority in the US House of Representatives will vote to block the Iran nuclear deal, a lawmaker announced Monday, but in numbers shy of the two-thirds required to torpedo the accord.
Congress will vote before September 17 on a resolution of disapproval of the agreement that six world powers reached with Tehran last month.
If the resolution is adopted, it would prevent President Barack Obama from lifting crippling US sanctions against the Islamic republic in exchange for the rollback of Iran's nuclear program.
Republicans control both the House and Senate, and such a motion appears on track to pass both chambers -- but Obama would veto it.
Overcoming the presidential veto would require a two-thirds majority in both chambers, a difficult challenge if most Democrats remain loyal to the president.
House Republican Peter Roskam said Monday that 218 of the 434 current members have committed to voting for the disapproval resolution which he introduced in July.
All are Republicans, and to date some in the party have yet to express their backing.
"Congress and the American people believe a better agreement is still achievable, and we can start by walking away from this one," Roskam said.
"We will do everything in our power to stop an accord that so utterly fails to shut down Iran's nuclear program."
On the Democratic side, several key lawmakers -- fervent allies of Israel -- have remained quiet on the accord, including Senator Chuck Schumer of New York and congressman Eliot Engel, top Democrat on the House Foreign Affairs Committee.
Some figures like Nancy Pelosi, the top House Democrat, have expressed unequivocal support for the deal.
The current House breakdown is 246 Republicans and 188 Democrats. A Republican seat is vacant and will be filled in a September 10 election, bringing the total again to 435 representatives.
The two-thirds threshold is 290.
The Senate, where the two-thirds threshold is 67, consists of 54 Republicans and 46 on the Democratic side, including two independents.