President Boris Yeltsin described the killing of Viktor Mosolov, the second such official to be murdered in 10 days, as a "terrorist act" aimed at intimidating voters before Sunday's vote. But the police ruled out a political motive.
His death, which follows a bomb attack on the running- mate of Moscow's mayor, has added to the pre-election jitters and led police to step up security markedly. Scores of lorries were being held up for searches on the roads into the capital.
Mr Yeltsin's response owes much to his desire to present himself as a candidate for stability in the closing stages of his campaign. He wastes no opportunity to depict his Communist rival, Gennady Zyuganov, as a man surrounded by dangerous revolutionaries, despite Mr Zyuganov's efforts to establish his credentials as a progressive, moderate Russian nationalist.
Yesterday Mr Yeltsin was at the Winter Palace in St Petersburg, a setting clearly chosen for its symbolism: it was stormed by the Bolsheviks at the start of the 1917 revolution. "On June 16, you will decide Russia's fate for many years ahead," Yeltsin told thousands of cheering young people, "The revolution started here in St Petersburg but Russia does not need any more revolutions.
But Mr Zyuganov also turned the metro bombing and the mayor's murder to political ends, by blaming government policies for a rise in mafia- style gangsterism and violence. "Unfortunately we pay for these policies with someone's blood every day," he said. Mr Zyuganov, a usually lacklustre figure who heads of the Communist-nationalist coalition, said that he had "practically won" Sunday's elections, and dismissed two polls giving Mr Yeltsin a 10-point lead.
Today Mr Yeltsin moves to his home town, Ekaterinburg, for a grand finale to his campaign which will be televised.
As he does so, the attention of some analysts is beginning to drift to the fortunes of Alexander Lebed, a pro-reform candidate who appears to be receiving discreet backing from the Kremlin on the grounds that he could take votes from the Communists. Speculation is growing that the popular retired general will form an alliance with Mr Yeltsin after the election's first round.