As the price tag for the U.S.-Iran war grows daily, Republicans who control Congress face a politically perilous path to funding the conflict.
When lawmakers return from recess next week, the GOP will confront a high-stakes push to approve new war spending amid questions about costs to date and how much more the administration will request. The White House has not provided a detailed breakdown; the Center for Strategic and International Studies (CSIS) has estimated the cost so far at nearly $30 billion.
Republicans are also constrained by the 1973 War Powers Resolution, which limits military operations to 60 days without congressional approval (with a possible 30-day presidential extension). That deadline has pushed several GOP lawmakers to voice public concerns that the conflict should be short or require explicit congressional authorization to continue.
Sen. Susan Collins, R‑Maine, criticized President Trump’s “incendiary” remarks and said she would not vote to send ground troops or extend hostilities past 60 days “unless there is a dramatic change.” “If the president commits boots on the ground, sends ground troops to Iran, I believe that congressional authorization for such action is completely required under the War Powers Act,” she said. Sen. John Curtis, R‑Utah, similarly wrote that he “will not support ongoing military action beyond a 60‑day window without congressional approval,” citing historical and constitutional reasons. Other Republicans expressing time‑limit or oversight concerns include Sens. Thom Tillis, R‑N.C., Todd Young, R‑Ind., and Reps. Don Bacon, R‑Neb., and Mike Lawler, R‑N.Y. Sen. Lisa Murkowski, R‑Alaska, has urged the administration to be more transparent with Congress, saying lawmakers are “learning through the media” and not getting public briefings.
Lawmakers are still awaiting clarity on how much additional funding will be sought. Republicans could pursue a supplemental appropriation or try to use reconciliation to insulate war funding from Democratic opposition. Last week, the White House asked Congress to approve roughly $1.5 trillion for defense in fiscal 2027, but it’s unclear how much of that would be tied to Iran.
Mark Cancian, a senior advisor at CSIS, said there has been discussion of a supplemental in the $80 billion to $100 billion range to cover war costs. He points to expensive munitions and damage to U.S. aircraft and infrastructure as major drivers of the CSIS estimate. The U.S. has reportedly fired more than 850 Tomahawk cruise missiles — more than in any previous U.S. war — at roughly $3.6 million each. Cancian said the U.S. may have lost about $1 billion in military jets and other aircraft, and that the dramatic rescue of two U.S. airmen in Iran, which involved the loss of several aircraft, may have cost about $500 million.
With slim majorities in both chambers, Republican leaders can afford few defections. Some conservatives have already opposed the war and are likely to resist funding: Sen. Rand Paul and Rep. Thomas Massie have co‑sponsored Democratic measures to limit the president’s war powers in Iran, Venezuela and other conflicts.
Democrats are working to block or complicate the GOP funding push and to put Republicans’ positions on record during an election year. House Democrats recently sought to force a vote to limit Trump’s war powers in Iran, and both House and Senate Democrats are expected to press for additional war‑powers votes next week. Senate Minority Leader Chuck Schumer, D‑N.Y., said, “No president, Democrat or Republican, should take this country to war alone. Not now, not ever,” and urged Republicans to join Democrats in approving the War Powers Act. House Minority Leader Hakeem Jeffries, D‑N.Y., argued that rising prices and the cost of military action give Democrats a campaign theme about affordability: “Gas prices are skyrocketing, the cost of living is out of control and billions of taxpayer dollars are being wasted dropping bombs in Iran, while Republicans refuse to spend a dime to make life more affordable for everyday Americans.”
Beyond direct government spending, analysts warn of indirect economic impacts for U.S. households through higher fuel, food and travel costs. Roger Pielke Jr., a senior fellow at the American Enterprise Institute, estimated a spike in gasoline and diesel through April 1 could cost Americans about $12.1 billion total, or roughly $92 per household, with higher jet fuel costs adding $2.2 billion through increased airfares and farmers facing about $131 million in added fertilizer costs.
Democrats themselves are not monolithic. Last month Sen. John Fetterman, D‑Pa., and Reps. Henry Cuellar, D‑Texas, Juan Vargas, D‑Calif., and Jared Golden, D‑Maine, voted against limiting Trump’s Iran war powers — votes that could shift as the debate continues. But if Republicans remain united behind the White House, Democrats may struggle to block funding.
Cancian said the lack of transparency from briefings and the absence of clear authorization have already been criticized, and rising costs will intensify scrutiny. “But as long as the president can hold the Republicans, the Democrats can’t do much,” he said.