Russians opened the door to Vladimir Putin (above) staying in power until 2036 by voting overwhelmingly for constitutional changes that will allow him to run again for president twice, but critics said the outcome was falsified on an industrial scale.

Official results, after 90 percent of ballots had been counted, showed that the former KGB officer, who has ruled Russia for more than two decades as president or prime minister, had easily won the right to run for two more terms. That means he could remain president for 16 more years...