WASHINGTON (Reuters) - U.S. Republican presidential candidates took swipes on Tuesday at the lifting of sanctions against Iran, but they disagree on how they would to handle Tehran if they win the White House at the Nov. 8 election.

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Iran can expect an abrupt shift in relations with the United States to a more aggressive posture under a Republican president, a reversal of the warming trend nurtured by Democratic President Barack Obama.

With only two weeks to go before the first nominating contest in the presidential race, Republican candidates have devoted large sections of their stump speeches to Iran, giving Tehran as much time as they devote to their condemnations of Islamic State militants, also known as ISIS.

“I would say this,” Former Florida Governor Jeb Bush told the Council on Foreign Relations in New York on Tuesday. “The convergence of an aggressive Iran in the region and ISIS are the two threats that we have to deal with and from day one we have to confront those ambitions.”

Obama has carried out a 2008 campaign pledge to negotiate with Iran by striking an agreement last year to curb Tehran’s nuclear ambitions. That deal was capped over the weekend when the United States along with other countries lifted sanctions against Iran, and Washington swapped prisoners with the Islamic Republic.

While Republican condemnations of Obama’s Iran policy abound, there is a split among the candidates as to how far to go with Tehran.

U.S. Senator Ted Cruz from Texas and U.S. Senator Marco Rubio say they would rip up the nuclear deal and start over, on the thinking that the United States would be able to persuade European allies to reimpose economic sanctions.

“The Europeans are going to have to decide do they want to deal with the Iranian economy or the American economy,” said Cruz foreign policy adviser Victoria Coates. “That’s the choice we have to put to them.”

A Rubio adviser said the Senator from Florida feels strongly that Iran had gotten the better of the Obama administration and that Rubio would only begin to discuss better relations with Tehran if it were willing to respect human rights and change its stance on Israel.

“I am going to cancel that ridiculous deal,” Rubio said last week in Mount Pleasant, S.C.

Other candidates like Ohio Governor John Kasich and front-runner Donald Trump are more cautious, preferring to wait and see what the situation is with Iran once the next president is sworn in on Jan. 20, 2017.

Kasich told Reuters that the United States should be working with U.S. allies now to ensure Iran sticks to the deal reining in its nuclear program and only if there are any violations the sanctions should be quickly reimposed.

“I think as time goes on it’s going to be harder because people are addicted to money,” he said. “I don’t know where we’re going to be in 10 months. No one knows where we’re going to be.”

Trump has said it would be tough to rip up the agreement with Iran on its nuclear program but has vowed that if he were elected president he would “police that contract so tough they don’t have a chance.”

Republican Senator John McCain, the party’s 2008 presidential nominee, told Reuters the argument over whether to stick to the Iran agreement is academic because he believes Iran will violate the nuclear deal.

“I think the best thing to do is evaluate it on Inauguration Day,” he said. “You’re going to have between the election and the Jan. 20 swearing-in to evaluate whether they have adhered to it and make a judgment then. But I think it’s a very bad agreement.”