During a news conference in Panama, President Obama lamented on the negativity surrounding a potential deal with Iran on its nuclear program. (WhiteHouse.gov)

President Obama said Saturday that he looks forward to engaging Congress in the coming week, not on the specifics of the framework agreement over Iran’s nuclear program, but on the “narrow question” of “what’s Congress’s appropriate role in looking at a final deal” to be negotiated by the end of June.

“I want to work with them so that Congress can look at this deal when it’s done,” Obama said at a news conference at the end of the Summit of the Americas here. “What I’m concerned about is making sure that we don’t prejudge it” and that “those who are opposed to any deal whatsoever try to use a procedural argument to screw up the possibility of a deal,” he said.

Obama was particularly critical of Sen. John McCain (R-Ariz.) who, he said, accused Secretary of State John F. Kerry of being “less trustworthy than the supreme leader” of Iran in explaining the specifics of the framework agreement completed early this month between Tehran, the United States and other world powers.

“That’s an indication of the degree to which partisanship has crossed all boundaries,” Obama said. “That’s not how we’re supposed to run foreign policy. When you start getting to the point that the U.S. government and our secretary of state are somehow spinning . . . that’s a problem. It needs to stop,” he said.

He also mentioned the letter sent to Iran’s Ayatollah Khamenei last month by 47 Republican senators warning Tehran that Congress had the power to intervene in any deal Iran made in the negotiations.

McCain quickly responded to Obama’s criticism, saying the administration and Iran had presented “widely divergent explanations” of what they had agreed to.

“It is undeniable that the version of the nuclear agreement outlined by the Obama Administration is far different from the one described by Iran’s Supreme Leader — on inspections, sanctions relief and other critically important issues,” McCain said in a statement.

Khamenei said Thursday that sanctions would have to be lifted on the day any deal is signed and that international inspectors would not be allowed to inspect Iranian military facilities. U.S. public statements about the deal have indicated neither of these are acceptable or were specified in the political framework.

“What’s always been clear,” Obama said, “is that Iran has its own politics around this issue . . . their own hard-liners . . . their own counterveiling impulses, just as we have in our country.”

“It’s not surprising to me that the supreme leader or a whole bunch of other people are going to try to characterize the deal in a way that protects their political position. But I know what was discussed in arriving at the political agreement,” Obama said. He always has the option not to sign a final document if it does not meet U.S. demands of closing all possible Iranian paths toward producing a nuclear weapon, Obama added.

Asked whether he thought Khamenei’s words should be “disregarded,” Obama said that “even a guy with the title of supreme leader has to be concerned about his own constituencies. The issue is not whether I have to take his word for whether that’s his understanding” of the agreement, he said, “because we’ve got until the end of June to see if we have a document that works.”

If Khamenei’s position “can’t be squared with our understanding and concern,” Obama said, “then we’re probably not going to get a deal.”

Highlights of the Iran deal