A Senate Energy and Natural Resources Committee hearing on the Responsible AI Energy Act devolved into pointed exchanges Friday between the chief executives of three of the country’s largest cloud and AI providers and a panel of senators increasingly willing to question whether the data center build-out can continue at its current pace while the United States is fighting a war that has pushed wholesale electricity prices to multi-year highs.

The session, which ran nearly four hours past its scheduled adjournment, marked the most substantive public airing yet of the moratorium bill introduced last week by Senator Bernard Sanders, I-Vt., and Representative Alexandria Ocasio-Cortez, D-N.Y., and it produced the clearest signal to date that the legislation may have a narrower path to Senate passage than the technology industry initially assumed. Two Republican senators — Josh Hawley of Missouri and Cynthia Lummis of Wyoming — pressed witnesses on grid reliability with a sharpness that surprised both colleagues and lobbyists watching from the gallery.

“You are asking ratepayers in my state to subsidize your training runs,” Hawley told Microsoft President Brad Smith during a tense back-and-forth over the company’s $1.2 billion data center expansion outside Kansas City. “When the war is over, what happens to those contracts? Do my constituents keep paying for your decision to over-build?”

Smith, appearing alongside Amazon Web Services Chief Executive Matt Garman and a senior Alphabet executive identified in the witness list as Vice President for Global Infrastructure Kavita Rao, defended the industry’s grid commitments and pointed to the joint hyperscaler letter sent Monday pledging more than $40 billion in transmission and generation co-investment over the next six years. He said a moratorium would “halt the very investments that the bill’s authors say are needed,” and warned that pausing permits would push capacity offshore.

The argument did not appear to land with the chair. Senator Joe Manchin, the West Virginia independent who runs the committee, allowed the hearing to extend well past lunch and pressed each witness on the same three questions: what share of their new capacity was tied to firm rather than interruptible power, what their actual water consumption per megawatt-hour looked like in the Southwest, and how much of their build pipeline assumed the continuation of expiring federal tax credits.

Garman acknowledged under questioning that roughly 38 percent of Amazon’s announced 2026 capacity in the United States remained on interruptible contracts, a figure that drew an audible reaction from the dais. Rao said Alphabet had paused two planned facilities in Arizona for water-availability review but declined to identify the sites.

The hearing’s most consequential moment may have come from a senator who is not on the committee. Senator Mark Warner of Virginia, who appeared as an invited member to question witnesses about Northern Virginia’s grid stress, told the panel that he would not commit to opposing the moratorium if it reached the floor in its current form. Warner, whose state hosts the largest concentration of data centers in the world and who has been a reliable industry ally, said the conversation around AI energy demand “has fundamentally shifted in the last thirty days.” Two Senate Democratic aides, granted anonymity to discuss whip counts, said Warner’s remarks would be studied carefully by the half-dozen Senate Democrats who had been considered persuadable on the bill.

Sanders, who attended the hearing as an observer rather than a witness, told reporters during a break that the testimony had reinforced his view that “the industry’s promises do not match what the grid operators are actually telling Congress.” He said he had spoken Thursday evening with Senate Majority Leader John Thune about a procedural path to a floor vote and was awaiting a response. Thune’s office did not respond to a request for comment Friday.

The administration has not formally taken a position on the bill, a silence that several senators noted from the dais. Energy Secretary Chris Wright, who declined an invitation to appear, sent a written statement that said the department was “evaluating the proposal’s implications for grid stability and national competitiveness” but did not endorse or oppose the measure. White House Press Secretary Karoline Leavitt, asked about the legislation at Friday’s briefing, said the administration “supports American AI leadership” but offered no further specifics.

The political backdrop made the hearing more consequential than its formal jurisdiction might have suggested. The Energy Committee does not have primary jurisdiction over the bill — that would fall to the Commerce Committee under Senator Ted Cruz, R-Texas, who has called the moratorium “a gift to Beijing” — but Sanders and his allies have been working to build the legislative record outside Cruz’s panel in advance of an expected procedural fight. A second hearing, before the Senate Banking subcommittee that oversees economic policy, is scheduled for Monday.

Outside the hearing room, the lobbying push intensified visibly. Chief executives of the three companies represented at the witness table held back-to-back meetings Friday afternoon with members of the Senate Democratic caucus, according to two industry sources familiar with the schedule. A coalition called Americans for AI Progress, funded in part by hyperscaler-affiliated trade groups, ran full-page advertisements in three Washington-area newspapers warning of “an unprecedented surrender of American technological leadership.”

Sanders and Ocasio-Cortez, who appeared together at a brief press conference in the Senate swamp after the hearing, said they expected the bill to receive a Senate floor vote no later than the week of April 6. Senate aides said additional procedural steps would be announced after the Banking subcommittee session Monday.