Early results show strong backing for reforms extending Putin rule
With results counted from just over four percent of polling stations, nearly 70 percent of voters had backed the reforms, the commission reported on its website.
Results of the six-day vote were being released from Russia's sparsely populated Far East, where polls had already closed, as voters continued to cast ballots in more populated areas including Moscow.
The commission said nationwide voter turnout was at nearly 63 percent.
Russians began voting last week on the package of constitutional changes proposed by Putin, including a reset of presidential term limits that would allow him to run twice again after his current six-year term ends in 2024.
Other amendments would strengthen presidential and parliamentary powers, enshrine traditional values including an effective ban on gay marriage and guarantee better minimum wages and pensions.
Russia's two houses of parliament have already approved the amendments but Putin said they would only take effect if supported by a majority of voters.
Initially planned for April 22, the vote was postponed by the coronavirus outbreak but rescheduled after Putin said the epidemic had peaked and officials began reporting lower numbers of new cases.