Because the CR will include appropriations for all cabinet departments, it’s very likely – if not almost certain – that there will be at least one attempt in the House and Senate to include language that prevents from using any of the funds to implement the deal.
That’s not to say this proposed language will survive, but the process will further slow down a debate on the CR that already was pushing against the time limit.
Even more important is that an effort to stop the Iran deal in the CR will provide a second take-no-prisoners issue that will further intensify the politics for many Republicans. When combined with the expected efforts to defund Planned Parenthood, it will add significant highly emotional fuel to the partisan fire and make a government shutdown far more politically palatable.
If that wasn’t enough, neither Iran implementation nor Planned Parenthood funding has anything to do with the big budget issue — military vs. domestic spending — that still must be resolved in the continuing resolution. There doesn’t seem to have been any progress whatsoever on the dispute between Republicans, that want to increase military and cut domestic programs, and the White House, that wants to increase them both.
And somehow this all has to be worked out quickly. Yes, there are only three weeks between now and the start of fiscal 2016, but the debate and votes on the CR have to be completed in the 10 days Congress will be in session before October 1. But because several of these days will be devoted to the Iran deal and Pope Francis’ visit to Washington, Congress and the White House really only have about seven days left to get all of the work done.
I would put the likelihood at 90% or higher. Once again, there's no way John Boehner will be able to deliver his caucus for a continuing resolution in the House, and with Sens. Cruz, Paul and Rubio all looking for a way to get back into the race, whoever shuts down the government first wins in the Age of Trump.
It's going to be a meltdown, and Republicans will get blamed again.
Whether or not that actually hurts the GOP, well, who knows. It certainly didn't hurt them in 2014.