Washington (CNN) Colorado Gov. Jared Polis on Sunday said he is worried about the potential for a second spike in coronavirus cases as the state begins loosening restrictions this week.

The Democrat announced early last week that the state would move into a " Safer At Home " phase on Monday, April 27, in which residents would not be ordered to stay in their home but are encouraged to stay there as much as possible. Polis told CNN's Jake Tapper on "State of the Union" Sunday that the more aggressive, stay-at-home measure "has been effective in leveling and plateauing the curve which is absolutely critical if we're going to in ... any way sustain the social distancing," while adding, "We don't even have an end date in sight until there's a vaccine or cure."

Asked about a warning from the Colorado School of Public Health about the threat of a second spike in cases, Polis told Tapper, "Yeah, we're all worried about a potential for a second spike, whether it's in the Fall, along with flu season in September/October, whether it's July."

"It's why we've really been really laser focused as an administration on figuring out how we can endure and sustain," he added.

The governor, when asked if he would reissue another stay-at-home order if he saw a new surge in Covid-19 cases, told Tapper he would look at data and "adjust in real time" as needed.

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