 Popa signed his name to a public protest decrying vote-rigging during the November 1946 election; there were ten other signatories, including aviatrix Smaranda Brăescu and Army General Aurel Aldea.It reached the Allied Commission, and, after being examined by Soviet representatives, served as incriminating evidence for the protesters' repression.Popa's final public appearance took the form of a speech before the Academy in April 1947.