In the event of force majeure, Law No. 44-FZ already provides for the right of the customer to promptly purchase any necessary goods from a single supplier.
It is worth noting that such a purchase from a single supplier is carried out according to universal rules of the law (including requirements for non - exceeding financial security over the limits of budget obligations brought to the customer), except for the absence of bidding (competitive procurement) - which is justified, since time costs and lengthy bidding procedures are unacceptable when force majeure circumstances occur and a high-readiness regime is introduced.
The full text of the letter can be found here.