Sens. John McCainJohn McCainTop commander: Don't bet on China reining in North Korea Trudeau, Trump speak for second night about US-Canada trade McCain: China has done ‘nothing’ on North Korea MORE (R-Ariz.) and Lindsey GrahamLindsey GrahamTop admiral: North Korea crisis is 'worst I've seen' Comey to testify before Senate Judiciary Committee Overnight Defense: US moving missile defense system to South Korea | Dems want justification for Syria strike | Army pick pushes back against critics of LGBT record MORE (R-S.C.) warned against delaying tough sanctions on Iran Wednesday.

Secretary of State John Kerry has asked the Senate to delay action on the sanctions at least until the United States and its partners meet next week with Iranian negotiators in Geneva. But McCain and Graham say the president is weakening his negotiating position.

“The administration should not weaken the strong negotiating position Congress has helped to create,” McCain said on the Senate floor.

Congress has consistently voted to strengthen sanctions against Iran and companies that do business with the country in order to force Iran to pursuing a nuclear weapons program.

The administration argues imposing new sanctions could derail any hope of avoiding a military clash over Iran's nuclear program, but Graham said, “no one wants another war.”

“The president’s eagerness to reach a deal is unnerving,” Graham said. “The way this deal is handled is probably most import decision President Obama will make in his second term.”

McCain and Graham said the administration should not give Iran anything until it stops enriching uranium — a process in developing nuclear weapons.

“What’s a good deal? To make sure the Iranians have a peaceful nuclear power program but can’t get a bomb,” Graham said. “If they keep enriching that tells you all you need to know about what their true intent is.”

McCain said getting an agreement for the sake of getting an agreement would be a “disaster.” He added that the United States should stand strong against Iran to support U.S.-ally Israel.