Discussions were scheduled to continue through Thursday between Iranian Deputy Foreign Minister Abbas Araqchi and EU political director Helga Schmid, to be joined by US Undersecretary of State Wendy Sherman and other negotiators on Friday. For the time being, these talks will proceed without Sherman and Araqchi’s superiors in the State Department and Foreign Ministry, although Secretary of State John Kerry and Foreign Minister Javad Zarif are expected to discuss the issue on Monday when both attend a United Nations review conference for the Nuclear Nonproliferation Treaty.

With the deadline just over two months away, the negotiations are apparently proceeding for now without an all-hands-on-deck mentality, even though essential issues remain unresolved, the final deadline has been twice extended, and negotiators missed an end-of-March deadline for a framework agreement that was ultimately announced on April 2, only to have details disputed in subsequent days.

A major disputed point involves the timing of the removal of sanctions, and Reuters indicates that this may be a sticking point for an agreement. Reuters also reports that Araqchi has expressed both optimism and insistence ahead of the resumption of negotiations, saying both that he believes a final agreement is attainable and also that Iran will not agree to any deal that leaves sanctions in place long enough to confirm Iranian compliance with the terms of that deal.

Meanwhile, President Obama has not committed to the opposite proposition, thus leading his critics to fear that another major concession will be given away to Iran as talks proceed. Obama has taken the position that continuation of sanctions is less important than their being able to snap back into place in response to signs of Iranian cheating. But Western lawmakers are not generally convinced that “snap-back” is a realistic proposition or that the emerging deal will do enough to guarantee that Iran’s nuclear work is sufficiently restrained.

A New York Times article sought to reassure readers on this latter point on Wednesday by detailing the several American nuclear laboratories that have been involved in setting the limits of negotiations and advising the Obama administration about what provisions would keep Iran more than one year away from being able to break out to nuclear weapons capability. But even if policymakers are convinced that this oversight has been effective and has been followed by the administration, the fact remains that the nature of these restraints is a separate issue from the verification that Iran is abiding by those restraints. And recent Iranian statements have raised questions about the regime’s willingness to allow such verification.

Breitbart points out that there has been a great deal of back-and-forth between Iran and the US on the matter of inspector access to suspicious sites in Iran. The US fact sheet on the preliminary agreement says that Iran will be required to grant the International Atomic Energy Agency access to any place thought to be linked to the nuclear program and US Energy Secretary Ernest Moniz insisted that “anytime, anywhere” inspections would be a key part of whatever agreement might be reached before June 30.

But Iran has disputed the veracity of this fact sheet and Iranian officials including Brigadier General Hossein Salami have declared that under no circumstances will foreign entities be allowed to inspect Iranian military sites. Breitbart reports that Behrouz Kamalvandi, a spokesperson for the Atomic Energy Organization of Iran, became the latest to reiterate this point on Monday. The sentiment has been similarly backed up by Supreme Leader Ayatollah Ali Khamenei, who has ultimate authority over all matters of Iranian policy.

This can be expected to spell trouble for the ongoing negotiations, especially if the US Congress wins its anticipated oversight of whatever deal emerges from executive-to-executive negotiations. South Carolina Republican Senator Lindsey Graham said that a deal that does not include provisions for “anytime, anywhere” inspections would not get past a Senate vote, according to the Jewish Press.

“Don’t think there’s a snowball chance in hell that Congress is going to approve this framework the way it’s set up,” Graham said, referring to Khamenei’s characterization of the emerging deal as something that allows Iran to receive immediate, large-scale sanctions relief upon signing, without committing to intrusive inspections.

A floor vote is pending on in the Senate for the bill that would give Congress the authority to reject such an agreement, and that bill enjoys strong bipartisan support which is expected to be capable of overriding a presidential veto.