Putin's popularity has taken a hit during coronavirus, but his approval ratings are still high.
Russia has been one of the countries hardest hit by the coronavirus pandemic -- ranking behind only the United States and Brazil in Covid-19 case numbers -- and the government's response has received heavy criticism at home and abroad.
The referendum vote, originally scheduled for April 22, was delayed amid coronavirus concerns. Election officials said early voting would be held to aid social distancing: Russia is still reporting around 7,000 new cases each day, according to official statistics.
Russian doctors have described critical shortages of equipment, a situation that hospital administrators and local governments deny. Observers have questioned whether Russia is under-reporting mortality figures from the deadly disease. But Kremlin spokesman Dmitry Peskov -- who has returned to work after being hospitalized with Covid-19 in May -- defended his country's handling of the pandemic.
In an exclusive interview with CNN last month, Peskov said the virus had not posed a domestic political crisis for Russian President Vladimir Putin, and that Russia's healthcare system had saved lives despite coming under major strain.
The pandemic dented usually sky-high ratings for Putin. Independent pollster Levada-Center noted that the Russian President's ratings fell below 60% in April and May, levels not seen since he assumed office two decades ago -- a drop that Peskov dismissed.
"We are concerned about this pandemic, and we are concerned about the impact of this pandemic on the country's economy," Peskov said on Tuesday. "But President Putin has stated numerous times that he doesn't care about his personal ratings, that in politics if you are real statesman, you should not think about your ratings -- because if you think about your ratings, you won't be able to take responsible decisions."