US President Obama fiercely defended the framework nuclear agreement with Iran and criticized those Republicans he said were politicizing foreign policy and working to derail the deal, according to New York Times.

“I don’t understand why it is that everybody’s working so hard to anticipate failure,” Obama said of the negotiations to hammer out a final nuclear accord, during a news conference at the end of a summit meeting of Latin American nations here.

“My simple point is let’s wait and see what the deal is,” he said.

He also said he remained “absolutely positive” that if a final agreement codified the commitments agreed upon earlier this month, it would be the best way of preventing Iran from obtaining a nuclear weapon. And he said that he was worried that Republican critics of the deal were trying to “screw up” its completion.