Top Republican senators accuse the White House of dissembling on Covid aid amid pleas for more funds.

The Republican senator who had been leading negotiations with the White House over new pandemic relief funding accused the Biden administration on Thursday of giving him “patently false” information when it said it was out of money to buy more coronavirus vaccines and treatments, in a tense exchange that appeared to further dim the chances of Congress approving new funds.

Senator Mitt Romney, Republican of Utah, said during a heated Senate health committee hearing that he was stunned last week when White House officials announced they would repurpose $10 billion in federal Covid-19 dollars meant for virus testing and protective gear and instead spend the money on antiviral drugs and vaccines. That, he maintained, meant the administration was not out of money for coronavirus supplies after all — even though the White House has made clear it would be shortchanging some types of supplies by redirecting funds to replenish others.

Administration officials have said for months that unless Congress authorized new spending, they would be unable to buy more pills and shots in anticipation of a possible fall wave. The White House has asked Congress for $22.5 billion in emergency relief; Mr. Romney helped negotiate a $10 billion compromise, which remains stalled.

“Washington operates on a relationship of trust between the respective parties, the administration and Congress,” Mr. Romney said, “For the administration to provide information to us that was patently false, is something which dramatically attacks that trust.”

Dawn O’Connell, the assistant health secretary for emergency preparedness and response, testified that the administration had to make “significant trade-offs — trade-offs that we none of us wanted to make” — in rerouting the $10 billion.

She said the money come in part from the administration’s coronavirus testing program, and from the Strategic National Stockpile, the nation’s emergency medical reserve, which she said would be not be able to purchase domestically manufactured surgical gowns, and will “struggle to be able to maintain” its current levels of protective gear as a result. Stockpile shortages were a major problem early in the pandemic, when many health care workers were infected or died for lack of necessary protective gear.

Mr. Romney’s comment reflected a broader political theme that Republicans are likely to raise during in their midterm election campaigns: that the administration had wasted Covid-19 relief dollars, an accusation that the White House has sought to refute. Jenn Psaki, the former White House press secretary, brought a 385-page briefing book to the White House press room in April, which she said detailed what money had been spent, when and for what reason.

“We’ve also given Congress a full accounting of every dollar that’s been spent,” Ms. Psaki said then.

Thursday’s session was the first Senate health committee hearing on the coronavirus response since January — a sign that interest in the pandemic is waning on Capitol Hill, as well as around the country. Dr. Anthony S. Fauci, President Biden’s chief medical adviser for the pandemic, testified remotely from home, where he is isolating after testing positive for the coronavirus. Dr. Rochelle Walensky, the director of the Centers for Disease Control and Prevention, and Dr. Robert Califf, commissioner of the Food and Drug Administration, also testified.

Each of the witnesses made a plea for more money; Dr. Walensky, for example, said that without a fresh infusion of funds the C.D.C. would not be able to continue surveillance studies, including “comprehensive monitoring of post-Covid conditions” and studies of new mothers with Covid, and how their illness affects their babies.

Republicans have insisted that any new money be offset with cuts to other programs. Senator Richard Burr of North Carolina, the ranking Republican on the health committee, closed the hearing with a blistering assessment, accusing Democrats and the White House of “trying to pressure Republicans to open a checkbook, sign the check and let the administration fill in the balance with no detail on how when or what was being asked for.”

“Nobody has worked harder on this issue, I think, on the Hill than I have,” Mr. Burr went on. “Nobody’s gone to bat for emergency money with no strings attached more than I have. But there is a point in time where my patience runs out.”

Mr. Romney — the 2012 Republican presidential nominee— sounded more hurt than angry. He said would not have “worked as hard” over “many weeks and intensive negotiations” if he had known other money was available.

“We should be apprised of what those trade-offs are, and have that discussion and help make that decision together,” he told Ms. O’Connell. “You shouldn’t be able to say, ‘Hey, we’re looking at trade-offs. We’re not going to tell you about them.’ ”