The State Department is locked in a fight with Senate Democrats over a giant Venezuela oil deal. Four senators are demanding details of the agreement with North American Blue Energy Partners.

Senators Jeanne Shaheen, Jack Reed, Martin Heinrich and Elizabeth Warren wrote to the department on September 30. They challenge the Pentagon’s plan to take a 35 percent passive stake in NABEP, Venezuela’s second-largest oil producer.

The deal covers 17 oil blocks with about 65 billion barrels of reserves. Under the plan, Venezuelan authorities granted NABEP arrangements covering 17 oil fields with about 65 billion barrels of reserves. The Pentagon’s Office of Strategic Capital would take a 35 percent passive stake through penny warrants, while the State Department would get preferential rights to 20 percent of output at cost.

The department’s Dylan Johnson said the senators had known for weeks that officials planned to brief them with documents on Thursday. He said the senators canceled the meeting and called their letter “pure grandstanding.”

Democratic aide comments accused the department of trying to dodge scrutiny as senators left town. President Trump has called it “the biggest oil deal in world history.”

The fight could slow approval of the deal. Democrats want guarantees it does not violate sanctions law.