WASHINGTON (AP) — Republicans and Democrats are pressuring congressional negotiators to produce legislation imposing the severest penalties on Iran, targeting its energy sector and financial institutions as the United States seeks to weaken Tehran economically and derail its pursuit of nuclear weapons.

With just one week before Congress’ August break, proponents of tough sanctions see this as their last, best chance after recent high-level talks between world powers and Iran have failed to curb its uranium enrichment. Iran insists that its program is solely for peaceful purposes.

“Now is the time to ratchet up the pressure,” Rep. Ted Deutch said in an interview this week.

Iran sanctions is one of the few issues in Congress that has strong bipartisan support as lawmakers look to thwart Iran’s nuclear objectives and show Israel the steps they are willing to take on behalf of the Mideast ally. Last year, the Senate voted 100-0 for legislation that targeted financial institutions that do business with Iran’s Central Bank

Rep. Ileana Ros-Lehtinen, chairwoman of the House Foreign Affairs Committee, and Sen. Tim Johnson, chairman of the Senate Banking Committee, have been negotiating behind closed doors for several weeks to reach consensus on sanctions legislation that the House passed in December and the Senate approved in May.

About a half-dozen Republicans and Democrats who favor fierce penalties have been insisting to negotiators that a watered-down bill is unacceptable.

“We owe it to the American people to exhaust every possible non-military option to prevent Iran from acquiring a nuclear weapons capability,” Sen. Mark Kirk said in a statement.

Rep. Robert Dold and Rep. Brad Sherman sent a letter this week to the negotiators calling for a final bill that includes a provision declaring Iran’s energy sector “a zone of proliferation.” The blacklisting would bar all transactions with the state-run National Iranian Oil Company.

“This would have the effect of making virtually any transaction with — and provision of services for — the firms in Iran’s energy sector sanctionable,” Dold and Sherman wrote.

The lawmakers also said any legislation should include sanctions on insurance companies that knowingly provide coverage to an entity that has already been penalized.

“If diplomacy is to succeed in ending Iran’s nuclear weapons program, we must enact tough legislation now,” the two wrote. “Sanctions are having a real impact on Iran’s economy, but not yet enough to change the regime’s strategic calculus.”

The bill the House passed last year would restrict foreign subsidiaries of U.S. companies from doing business with Iran. Bartering is included among the activities that could be sanctioned, and Americans would be prohibited from conducting commercial or financial transactions with Iran’s Revolutionary Guard Corps.

The Senate-passed bill would target the Revolutionary Guard, require companies that trade on the U.S. stock exchange to disclose any Iran-related business to the Securities and Exchange Commission and expand penalties for energy and uranium mining joint ventures with Tehran.

The bill also would deny visas and freeze assets on individuals and companies that supply Iran with technology that could be used to crack down on its citizens, such as tear gas, rubber bullets and surveillance equipment.

Copyright 2012 The Associated Press.