This article is from the archive of our partner National Journal

As President Obama and congressional supporters of the pending Iran nuclear deal are about to find out, 60 days is a long time.

From the White House Tuesday morning, Obama announced the nuclear agreement with Iran -- threatening to veto any move that would scuttle the deal. It was an early start in what will be a hot summer of debate that will officially kick off when the final text is be delivered to Congress for review later this week or early next. That will start the clock that gives lawmakers 60 days to disapprove of the deal, rubber-stamp it, or ignore it altogether and allow it to go through without congressional input.

Democrats had pushed for just a 30-day review period, but in a compromise with Republicans agreed to extend it for 60 days if negotiators failed to meet a July 9 deadline. As negotiations continued, members are now left with two months to think over the deal, about half of which will be spent at home in their districts hearing from constituents concerned about a nuclear Iran and seeing their own faces on television in a barrage of ads from outside groups.

It all adds up to a headache for vote-counters on both sides of the issue.

The ad war has already begun, and it only promises to grow more intense with a deal on the table and members of Congress far away from their peers in Washington during the August recess.

And the issue is already bubbling up among the public, Republican pollster David Winston said. Although Iran remains far behind jobs and the economy as driving issues for voters, he said, "in a lot of polls it's right around double digits," much higher than is typical for a foreign policy issue. But along with the issue of ISIS, Winston said, "there are very clear potential outcomes that are very clear significant threats" and the American public is paying attention.

"The bigger challenge and the bigger question is going to be, and it depends on how this [deal] gets shaped: ... Is this a deal that people believe will allow Iran to create this weapon or not?" Winston said.

How that message is shaped will, in part, be up to ad-makers who are already running television spots encouraging members to oppose the (as-yet-unannounced) deal with Iran. The ads have largely targeted Democrats, who will be swing votes on the biggest foreign policy deal of President Obama's tenure.

Democratic Senatorial Campaign Committee spokesman Justin Barasky said that the issue can also be used in Democrats' favor, noting voter discontent with Senate Republicans' open letter to Iran earlier this year and the near shutdown of the Department of Homeland Security. "I do think it's something Republicans are vulnerable on. "¦ I think they're the ones that are going to have to deal with the voters in a way that's problematic," Barasky said.

But members on both sides of the issue say they can handle a barrage of ads and political attacks if it means more time to consider the details of the Iran deal.

DSCC chairman Jon Tester said he's already faced opposition ads on the Iran deal, even though he isn't up for reelection until 2018 and there's not yet a deal to oppose. But Tester said he is not worried about how the ads will affect his colleagues, including those who are facing reelection this cycle. "Look, I think that [if we] get a good deal—it's a deal that has good oversight and keeps Iran from being nuclear—I think that's a win-win. Now, you don't get a good deal, you don't vote for it," he said.

"There's already been ads out there in different parts of the country for those who are against and those who are for," said Democratic Sen. Robert Menendez, the former chairman of the Foreign Relations Committee. "That will neither enhance it nor stop it at the end of the day."

Sen. Ben Cardin, the ranking member on the Foreign Relations Committee, has already been the subject of negative campaign ads on Iran, but said he's not worried about advertising and political campaigning changing too many votes either. Those outside groups have lost a lot of "integrity," Cardin said, for pushing so heavily in favor or in opposition to the deal before there even was a deal to discuss.

"The funny thing is, one of the people who's normally involved in those ads called me to tell me, 'Why are we doing [this]?' They were surprised," Cardin said. "There's no agreement. Until there's an agreement, it's premature."

Once an agreement is publicly available, both sides will have the opportunity to air their grievances either in the halls of the Capitol or on the airwaves, Foreign Relations Chairman Bob Corker said. "Whether you're at recess or no recess, this is going to be one of those issues that's going to be highly, highly discussed and there are going to be both sides pushing hard," Corker said.

Corker, who always favored a 60-day review period, said that the additional time "causes the process to be more thoughtful."

Even Cardin, who pushed vigorously for a 30-day review period, said that he's now hopeful that 60 days will allow members to do the heavy lifting on the deal, holding hearings and getting into the details, before they break for August recess. Then members can go home armed with information and spend the month engaging in a positive, national discussion of the issue.

"We have right now four weeks left in this Congress," Cardin said. "If we use those four weeks to do the public hearings, to do the briefings, etc.—have a robust, open process, that complements, I think, a public understanding—and then the August recess could be even more productive "¦ and just maybe you'll see more unity in this country than you'd expect. I don't know where it's going to be, but there could be more unity coming out here than one would have anticipated. "¦ I think it will be very healthy for this country."

With an issue as consequential as nuclear weapons in Iran, Winston said, that is a possibility. The pollster said that while he expects outside groups to advertise on the issue, the public is likely to take a much deeper look. "People may notice these ads," Winston said, "but this is ultimately going to be a discussion about substance because, again, the stakes are so high. ... They're going to want more information than just an ad."

This article is from the archive of our partner National Journal.

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