This sentiment was expressed to Reuters by one anonymous senior diplomatic source, who was quoted as saying, “I believe monitoring and inspections may prove to be the most difficult nut to crack and I wouldn’t be surprised if Iran and the P5+1 have some big fights about it.” The prospect of “big fights” at this stage of the negotiations may spell trouble for the tight timeline that both sides are now facing. With only about two and a half months remaining in negotiations and very few points definitively agreed even after the announcement of a framework deal, the negotiating powers will have many details to work out before being able to finalize a document.

The deadline for these talks has been extended twice already – once last July and again in November – but a third extension has been all but ruled out by officials on both sides. Changing political situations would make support for such an extension very sparse, and as it stands there is much skepticism or outright opposition to the emerging deal among members of the US Congress and hardliners in the Iranian government.

What’s more, the views of those hardliners are potentially gaining traction from the recent comments on the emerging deal by Iranian Supreme Leader Ayatollah Ali Khamenei, who is the ultimate authority in all matters of Iranian policy. For the time being, Khamenei has described himself as being “neither for nor against” the deal, but he has also reiterated longstanding demands that are unacceptable to most Western policymakers, and that may even be logistically impossible. These include demands for immediate removal of all economic sanctions as soon as a deal is signed – something that is at odds with the American understanding of what was agreed to on April 2.

In a blog post at the Wall Street Journal, Ray Takeyh of the Council on Foreign Relations analyzed Khamenei’s recent comments and contradicted the claims of some supporters of the negotiations who say that his demands are mere political theater intended to preserve hardline support or exert pressure for the best possible deal for Iran. Takeyh emphasized that Khamenei has directly undercut his own negotiators, thus making the conclusion of a final deal much more difficult.

In addition to the effect that Khamenei’s rhetoric will have on the negotiating process and the matching rhetoric of other Iranian regime officials, it can also be expected to further increase skepticism about Iran’s trustworthiness. The Times of Israel reported on Friday that a new NBC News poll finds that 68 percent of Americans already believe that Iran would not be likely to abide by a deal curbing its nuclear ambitions.

It is clear that this perspective is reflected in much of Congress, as evidenced by the bipartisan support for the Iran Nuclear Agreement Review Act, which the Senate Foreign Relations Committee may vote on as early as Tuesday. The deal in its current form would require that the US president prove on a regular basis that Iran is abiding by its obligations in order to keep sanctions against the Islamic Republic from snapping back into place.

Hot Air reported on Friday that at last count the legislation was four votes short of being able to override a presidential veto. As concerns over Iran’s reliability and its resistance to an appropriate inspections regime grow, Democratic support for the bill may grow as well. In fact, Hot Air quotes Democratic Senator Tim Kaine as saying that he does not believe the INARA will impair the nuclear negotiations as long as Iran is committed to acting rationally to get itself out from under sanctions. The support of this and other high-ranking figures in the Democratic Party may further bolster support.

And the views of the Democratic constituency may make such support quite plausible. An editorial in the Chicago Sun Times on Friday served to demonstrate, for instance, that among the Jewish population, one does not need to share Israeli Prime Minister Benjamin Netanyahu’s views on other issues in order to share his extreme anxiety about the prospect of a bad deal with Iran over its nuclear program. The article’s author described himself as a homosexual, Jewish liberal Democrat who is in favor of a Palestinian state and is “outraged” by some of Netanyahu’s policies, but who worries that some members of the US Congress are sitting on their hands in lieu of making concerted efforts to prevent Iran from obtaining a nuclear weapon.

Opinions vary both across party lines and within particular political circles as to what would constitute the appropriate concerted efforts. Conservative commentator Charles Krauthammer used a column in the National Review on Thursday to wonder why the Obama administration has not simply given up on the nuclear talks and turned to other measures of keeping Iran from obtaining a nuclear weapon. Krauthammer particularly highlighted the same issue that Reuters indicated may be the biggest stumbling block to the negotiations on both sides: inspections and verification.

Krauthammer referred to the inspection methods established by the framework agreement as a “farce.” He also questioned how willing the Obama administration and the international community will be to hold Iran to the promised inspection regime in light of the fact that they haven’t been holding Iran to its obligations under the long-delayed International Atomic Energy Agency probe of the past military dimensions of Iran’s nuclear program. This, Krauthammer claims, deprives the US of an appropriate baseline knowledge of Iran’s military program, which would be necessary in order to understand whether capabilities had been added.

Views of this sort contribute to the determination of a number of experts who say that in order to be effective, the verification methods established by a final agreement will have to include snap inspections of any suspect sites at any time. Reuters points out that this is the determination of both David Albright of the Institute for Science and International Security and Olli Heinonen, the former chief nuclear inspector for the IAEA.

But in light of the disagreements over the framework agreement and the rhetoric coming from the Iranian supreme leader, it seems clear that such intrusive inspections are not something that Iran will agree to readily, even with the clock ticking down to the final deadline for a deal.