MINNEAPOLIS (AP) — Democratic U.S. Sen. Tina Smith skipped a campaign event with Sen. Elizabeth Warren over the weekend after learning that a person who attended one of her events eight days earlier had tested positive for the coronavirus.

“I’m getting tested & I am quarantining until I test negative," Smith tweeted Sunday. After learning Monday morning that she had tested negative, Smith tweeted that she was “Headed back to Washington to keep working for Minnesotans.”

Campaign spokeswoman Molly Morrisey said the person who tested positive attended a lawn sign pickup rally at Smith's headquarters in St. Paul on Oct. 10. It was an outdoor event at which masks were required, and Smith did not have close contact with the individual, Morrisey said. The campaign learned Sunday that the person tested positive.

To be safe, Morrisey said, Smith got tested and skipped a Sunday afternoon rally with Warren, a senator from Massachusetts, at Macalester College in St. Paul.

Republicans U.S. Reps. Tom Emmer, Jim Hagedorn and Pete Stauber came under Democratic criticism earlier this month for flying back to Minnesota from Washington just two days after they had flown with President Donald Trump on Air Force One, where they potentially could have been exposed. That was before the White House announced that the president had tested positive for COVID-19. Their own test results came back negative before they flew on a Delta Air Lines flight. But Democratic leaders said they should have waited longer, given the virus' incubation period.

Smith's potential exposure was nine days before she tested negative.

Her Republican opponent, Jason Lewis, self-quarantined for a few days after greeting Trump at the airport in Minneapolis and flying on Air Force One to Duluth, and briefly again later after a campaign worker tested positive. They have clashed on the campaign trail over how strict state and national restrictions should be to slow the spread of the virus.

Lewis said there's a double-standard for Republicans and Democrats over COVID-19 rules.

“Tina now gets a free pass for doing the same,” Lewis tweeted Monday.