WASHINGTON -- Secretary of State John Kerry on Wednesday warned Congress against scuttling a historic opportunity for a nuclear pact with Iran by pressing ahead with new sanctions while international negotiators seek to prevent Tehran from being able to assemble an atomic weapons arsenal.
Mr. Kerry, who as a senator joined the effort to impose crippling oil, trade and investment restrictions on Iran, said the United States and other world powers are united behind an offer they presented to Iranian negotiators in Geneva last week. But he said new action now from U.S. lawmakers could shatter an international coalition made up of nations with interests as divergent as France, Russia and China, endangering hopes for a peaceful end to the decade-long nuclear standoff with the Islamic republic.
"We put these sanctions in place in order to be able to put us in the strongest position possible to be able to negotiate. We now are negotiating," Mr. Kerry told reporters ahead of testifying before the Senate Banking Committee. "And the risk is that if Congress were to unilaterally move to raise sanctions, it could break faith in those negotiations, and actually stop them and break them apart."
With nuclear negotiations set to resume in Switzerland next week, the Obama administration dispatched Mr. Kerry and Vice President Joe Biden to Capitol Hill on Wednesday to seek more time for diplomacy. They faced skepticism from members of Congress determined to further squeeze the Iranian economy and wary of yielding any ground to Iran in the talks.
At a House Foreign Affairs Committee hearing Wednesday, Democratic and Republican lawmakers sharply criticized Mr. Kerry and other senior U.S. officials for their offer during last week's inconclusive negotiations.
"The Iranian regime hasn't paused its nuclear program," lamented House Foreign Affairs Committee chairman Ed Royce, R-Calif. "Why should we pause our sanctions efforts, as the administration is pressuring Congress to do?"
Positions are more mixed in the Senate. After briefing the Banking Committee, Mr. Kerry and Mr. Biden gathered behind closed doors with Senate Democratic leaders to explain the administration strategy. No Democratic leader left the meeting contradicting the administration's call for caution on sanctions.
Mr. Kerry said the potential accord with Iran stems from a "tough proposal," adding: "If it weren't strong, why wouldn't Iran have accepted it yet?"
But the former Massachusetts senator said moving the goalposts amid the current talks' lull, by adding new sanctions against Iran's oil and other industrial sectors, would cause U.S. negotiating partners to see the United States as "dealing in bad faith."
"If this doesn't work, we reserve the right to dial back up the sanctions," Mr. Kerry said. "I will be up here on the Hill asking for increased sanctions, and we always reserve the military option. So we lose absolutely nothing, except for the possibility of getting in the way of diplomacy and letting it work."
He said negotiators should have a "few weeks" more to see if they can reach an agreement. The State Department's nuclear negotiator, Wendy Sherman, and the Treasury Department's sanctions chief, David Cohen, also joined him at the Capitol.
President Barack Obama has reached out in an unprecedented manner to Iran's new President Hassan Rouhani, with the two men holding the first direct conversation between U.S. and Iranian leaders in more than three decades. Yet at the same time, Mr. Obama has angered wary U.S. allies Israel and Saudi Arabia, which see an Iranian nuclear arsenal as existential threats.
Iran insists that its program is solely for peaceful energy production and medical research, but until recently had offered little to assuage Western and regional fears that it was secretly trying to develop atomic bombs.
Some in Congress are gearing up for a fight with the administration over the new sanctions, overwhelmingly approved by the GOP-led House in July. The legislation blacklisted Iran's mining and construction sectors and committed the United States to the goal of eliminating all Iranian oil exports worldwide by 2015. If the Senate Banking Committee stalls its parallel bill any longer, lawmakers could attach it to a Senate defense bill that may come up for debate as early as today.
Sen. Dick Durbin, the No. 2-ranked Senate Democrat, said in an interview that he supported delaying action on further sanctions as long as diplomatic progress was being made. Sen. Bob Corker, the Senate Foreign Relations Committee's top Republican, also sounded conciliatory, saying his focus was on maintaining existing restrictions on Iran's economy, so the United States keeps its negotiating leverage.
But Senate Foreign Relations panel chairman Robert Menendez, D-N.J., this week called for tougher sanctions as an incentive for negotiations, and many Republicans back him.
"We ought to be actually ratcheting up the sanctions against Iran," said Senate Minority Leader Mitch McConnell, R-Ky. "What the administration was promoting is something the Israelis think is a bad deal for them. It's pretty clear the Sunni Arab allies of ours also think it's a bad deal. Looking at it strictly from an American point of view, I think it's a bad deal as well."
Last week's talks came tantalizingly close to an accord. They broke down, diplomats said, as Iran demanded formal recognition of what it calls its right to enrich uranium, and as France sought stricter curbs on Iran's ability to make nuclear fuel and on its heavy-water reactor to produce plutonium.
Mr. Obama spoke by phone Wednesday with French President Francois Hollande. The two nations "are in full agreement" on Iran, the White House said.