He created a verb from the word zhid, a derogatory term for a Jewish person, to describe opposition activities.
This caused a chain of offended reactions by fellow bloggers, leading to another tweet from Isayev in which he explained that the slur was a linguistic error and accused those who had interpreted his statement as anti-Semetic of lying.
Isayev claimed he meant that the opposition was becoming "liquid," implying fewer in number. The Russian adjective for liquid shares the same root as a derogatory term for a Jew.
Borukh Gorin, spokesman for the Federation of Jewish Communities of Russia, criticized the original tweet but said there was no basis for accusing Isayev of anti-Semitism.
"In my opinion yesterday's statement was not ethical, but he himself says that he did not mean anything like 'that,' so I have no reason to accuse him of anything," he said, RIA-Novosti reported.