In its quest to build up its stockpile of COVID-19 drugs, the U.S. government has held talks with Japanese drugmaker Shionogi & Co. about buying its experimental antiviral pill, people familiar with the matter said. But finding the money to pay for it could be a problem.

Two years into the pandemic and after nearly a million deaths in the United States, a stalemate in Congress has left those in charge of building up the country’s drug supplies without the resources to do so. The implications are far-reaching. The government needs more funding to pay for existing orders with companies like Pfizer Inc. and could end up unable to invest in new therapies like Shionogi’s.

The talks to buy Shionogi’s drug have been preliminary, the people said, speaking on condition of anonymity because of the confidential nature of the discussions. The drugmaker’s treatment is currently in late-stage clinical trials and hasn’t yet been authorized. In earlier studies, the drug reduced viral loads in patients within the first few days of use.