By Mark Niquette

After Congress's deadline to block President Barack Obama's nuclear deal with Iran expired Thursday, Republicans are taking the fight to the states by vowing to preserve local sanctions.

Thirty states and the District of Columbia restrict investments by pensions and public entities in companies doing business in the country, according to the group United Against Nuclear Iran. Fifteen Republican U.S. governors, including four presidential candidates, last week sent a letter to Obama saying they would fight to keep their constraints if the administration lifts its nuclear-related sanctions.

A new nonprofit, Defund Iran, is also seeking state constitutional amendments next year that would mandate divestment. Florida alone has withdrawn more than $1.1 billion since 2007 from companies involved with Iran including Royal Dutch Shell Plc, Cnooc Ltd., and Daelim Industrial Co., according to Chief Financial Officer Jeff Atwater.

Republicans say Obama's agreement won't prevent nuclear proliferation, and will unleash Iran's economy and its ability to support terrorism. Focusing on states gives the party another angle of attack.

"It enables them to take a stand against President Obama and, in the bargain, take a stand for the rights of the states," said Jack Pitney, a political science professor at Claremont McKenna College near Los Angeles.

The lifting of federal sanctions would allow a few U.S. aerospace companies to seek business in Iran, such as Boeing Co. and General Electric Co., according to a report from Bloomberg Intelligence. Overseas firms including Shell and BP Plc also could seek business there, it said. States shouldn't help, said Sarah Steelman, chairwoman of Defund Iran and a former Republican candidate for U.S. Senate in Missouri.

The governors, including presidential aspirants Bobby Jindal of Louisiana, New Jersey's Chris Christie, John Kasich of Ohio and Wisconsin's Scott Walker, point to a provision in the deal that says the federal government will "actively encourage" state and local officials to "take into account" U.S. policy lifting some sanctions.

"We intend to ensure that the various state-level sanctions that are now in effect remain in effect," the governors said in their Sept. 8 letter.

With assistance from Darrell Preston in Dallas.

(c)2015 Bloomberg News