A day after President Obama suggested that Iranian hardliners and congressional Republicans had found "common cause" in opposing the recently negotiated nuclear accord, the Senate's top Republican accused him of trafficking in "crass political rhetoric" as he tries to sell lawmakers on the keystone of his foreign policy agenda.

"The president strikes me, at least so far, as treating this like a political campaign," McConnell said. "Demonize your opponents, gin up the base, get the Democrats all angry and, you know, rally around the president."

McConnell spoke during an unusually freewheeling 30-minute news conference, held the day after the Senate adjourned for its month-long summer recess. He sought to promote the accomplishments of the first Republican Senate majority in eight years, which includes the passage of major education, defense and transportation bills, as well as the approval of fast-track presidential trade authority and legislation establishing a formal congressional review of the Iran deal.

But an autumn of drama awaits, with a possible government shutdown looming at September's end, as well as a papal visit, another possible showdown over the federal debt limit, and more. First, though, the Senate will take up the Iran nuclear deal, which, under the review law, Congress has until Sept. 17 to review.

That means shortly after Labor Day, the chamber will convene for a floor debate where every senator is asked to sit at his or her desks, McConnell said, "actually listening to what others are saying."

"We're now entering into an agreement in which we are basically being asked to trust the biggest funder of terrorism in the world today, and so it's appropriate to have some skepticism about a debate of this magnitude," he said. "And regardless of how the president talks about it, regardless of what his incendiary rhetoric is, we're going to deal with this in a respectful way, dealing with the facts surrounding the issue and treat it with the dignity and respect that it deserves here in the Senate."

In his Wednesday address at American University, Obama noted that Iranian hardliners who are "chanting 'Death to America' ... have been most opposed to the deal" and are "making common cause with the Republican caucus."

White House Press Secretary Josh Earnest stood by that comment Thursday, calling it a "statement of fact" that he would not apologize for: "You have in Iran a group of hardliners who are strongly opposed to the deal and advocating for its defeat, and here in the United States, you have Republicans in Congress who are advocating against the deal and urging its defeat. ... So, the fact is, they've taken the same position."

Obama also reiterated his belief that a rejection of the deal would ultimately necessitate military action against Iran: "The choice we face is ultimately between diplomacy or some form of war. Maybe not tomorrow, maybe not three months from now, but soon."

That, too, incensed McConnell, who dismissed it as "an absurd argument" Thursday.

"That's never been the alternative," he said. "It's not this deal versus war. ... It's either this deal or a better deal, or more sanctions. And I think that's been a huge mistake on his part."

McConnell also approvingly referred to June comments from former President Jimmy Carter -- "We can probably stipulate that that has not been routine on my part," McConnell quipped -- in which Carter said, "I can’t think of many nations in the world where we have a better relationship now than we did when [Obama] took over."

"That's Jimmy Carter," he said. "I rest my case."

In other remarks:

• Amid growing speculation that Republican hardliners might try to use the Sept. 30 government funding deadline in order to force the defunding of Planned Parenthood, McConnell reiterated his determination to avoid a federal shutdown. "You may have heard me say this before, but one of my favorite old Kentucky sayings is, there's no education in the second kick of a mule," he said. "We've been down this path before. This is a tactic that's been tried going back to the '90s, frequently by Republican majorities. And it always has the same ending, that the focus is on the fact that the government is shut down, not on what the underlying issue that is being protested is." He later added, "I can tell you without fear of contradiction there will be no government shutdown."

• Asked if he saw any prospect for immigration reform legislation to pass before 2017, McConnell ruled it out: "Not this Congress." He said Obama had poisoned the well for bipartisan legislation by taking executive action to give illegal immigrants a path to legal status: "He pretty much made it impossible for us to go forward with immigration reform this Congress."

• Thursday was the 50th anniversary of the signing of the landmark Voting Rights Act of 1965, and McConnell recounted a personal story of watching President Lyndon B. Johnson sign the law during a chance visit to the Capitol as a young former intern. But McConnell said he did not see the need for congressional action to restore the portions of the law struck down by the Supreme Court in 2013, saying in response to a question that it is "important to understand how different the South is now." Said McConnell, "America's come a long way, and the Voting Rights Act is intact. It was not struck down."