Republicans and Democrats in Congress questioned Secretary of State Marco Rubio and U.S. special envoy Steve Witkoff on Monday, the first time they have briefed a broad group of lawmakers since the U.S. and Iran signed a June 17 memorandum of understanding to cease hostilities.

The MOU established a 60-day framework while the sides work toward a permanent deal.

The deal requires that Iran make its best efforts to ensure the safe passage of commercial vessels through the Strait of Hormuz in return for lifting the U.S. naval blockade of its ports.

Although Democrats asked some of the sharpest questions, participants in an afternoon conference call with House members told Politico that Rep. Darrell Issa, R-Calif., pressed Rubio and Witkoff on the fate of Iran's stockpile of near-weapons-grade uranium.

Witkoff and Rubio repeated assurances the administration has privately made to select lawmakers in prior briefings that the goal is to negotiate a final deal that would prohibit Iran from keeping its highly enriched uranium, Politico reported, citing two people granted anonymity to disclose the private remarks.

Witkoff added that the technical team involved in that part of the negotiations was traveling from Switzerland to Qatar, where talks are scheduled to resume Tuesday.

Democrats, meanwhile, pushed the administration for more details on what financial benefits Iran could reap under the MOU, including proceeds from previously sanctioned oil sales.

Rep. Debbie Wasserman Schultz, D-Fla., went back and forth with Rubio and Witkoff over the lifting of the oil sanctions, two other people granted anonymity on the House call told Politico.

The officials eventually cut off the conversation and ended the call.

At another point, Rep. Madeleine Dean, D-Pa., raised concerns about Witkoff's business interests in the Middle East as he's negotiating with Iran, prompting a sharp defense from Rubio.

Senate Minority Leader Chuck Schumer, D-N.Y., asked Rubio and Witkoff about the oil sanctions during a separate all-senators call Monday, saying in a statement afterward that they "confirmed to me that Iran will reap billions in oil revenue while retaining dangerous leverage over the Strait of Hormuz."

"If this is the administration's defense behind closed doors, Secretary Rubio should make it under oath, in public, before the Foreign Relations Committee," Schumer added, calling the briefing "delayed, deficient, and devoid of details."

An administration official, who spoke on condition of anonymity, said Schumer had previously received a briefing on the deal as part of a group of top congressional leaders engaged in national security matters.

The official said Schumer also had an opportunity to ask multiple follow-up questions during Monday's Senate call.

Sen. Steve Daines, R-Mont., called the Senate briefing a "productive conversation" but said "much of what I heard today is similar to what I heard last week" during a dinner at Vice President JD Vance's residence.

The House is in session this week, but the Senate is on a two-week July 4 recess.

A separate group of White House officials briefed top congressional leaders and key committee chairs in a classified briefing at the Capitol later Monday, according to Politico.

Rubio and Witkoff sought to ease concerns about the slow reopening of the Strait of Hormuz, the crucial global shipping route whose closure has sparked higher fuel and fertilizer costs.

More mine removal is required, and Witkoff indicated that Iran broke the terms of the deal by launching a drone attack on a commercial vessel over the weekend.

They also sought to assure lawmakers that Iran has received no money under the memorandum — especially not directly from American sources.

Administration officials have previously told lawmakers that a $300 billion reconstruction fund agreed to under the MOU won't include U.S. funds.