If Kerry does manage to seal a historic deal in the next few days, attention will immediately turn back to Congress, which voted earlier this year to give itself a say in the matter. Under the terms that lawmakers set for themselves (after some bargaining with the administration), it won’t be easy for Congress to stop the agreement, and the precise timing of the accord could have a significant impact on the outcome. If the administration submits the signed deal to Congress by Thursday, the House and Senate would have just 30 days to review and vote on it—a window that, in actuality, becomes even shorter since lawmakers are scheduled to leave for their sacred summer recess by the end of the month. If the Thursday deadline slips, then under the law Congress would have 60 days to consider the agreement.

“They’re rushing,” said Senator Bob Corker, chairman of the Foreign Relations Committee, in a Sunday appearance on Face the Nation. Corker’s implication? That the administration wants to jam Congress because the longer that lawmakers have to review the deal, the more likely they’ll be to oppose it. Josh Earnest, the White House press secretary, scoffed at that suggestion, telling reporters that the fact that it has taken two years even to get to this point “indicates that nobody’s been in a rush.”

The administration’s critics say that Obama and Kerry, in their desperation for a legacy achievement, have conceded far too much and crossed many of the red lines they once set. Inspections, critics worry, won’t be frequent enough, much less “anytime, anywhere”; sanctions would be lifted too quickly and would be harder to “snap back” into place than Obama has suggested; and Iran’s ability to acquire a nuclear weapon would merely be delayed, not eliminated. Reports on Monday indicated that Iran was pushing for a U.N. arms embargo to be lifted as part of the deal, which the U.S. has opposed. Still, because of the compromise Congress and the administration agreed to in the spring, opponents would need a two-thirds majority to block the deal, and that would require a large number of Democrats deserting the president. To that end, Obama has largely cleared his schedule this week in anticipation of an announcement, and he’s invited Senate Democrats to the White House on Tuesday night—possibly to lobby them on the agreement.

Lawmakers like to talk about asserting their prerogatives a lot more than they actually assert them, as Congress demonstrated by its inaction on a resolution authorizing Obama’s war against ISIS. It’s entirely possible that neither the House nor Senate will hold a vote on the Iran deal, in which case the deal would take effect after the 30- or 60-day window ends. But both chambers are getting ready to act. The House is “on high alert,” said Kevin Smith, a spokesman for Speaker John Boehner, and a hearing is already scheduled for Thursday in the Foreign Affairs Committee. In the Senate, Corker has been convening briefings for members ahead of an announcement. The party leadership could decide to hold votes just to put Democrats in a tough spot. “If this is a bad deal, Democrats are not going to be able to hide,” Smith told me.

Republicans might not be able to stop an agreement that they see as a capitulation to a dangerous regime, but it looks like they’re going to try.

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