Former North Carolina state Sen. Cal Cunningham, a Democratic challenger for Tillis' Senate seat, called out the Republican lawmaker not telling those around him to cover their faces as a double standard.

"Sen. Thom Tillis criticized folks for not wearing masks, until Washington Republicans were the culprits. His attendance last night shows North Carolinians that the rules don’t apply to his colleagues in Washington — and that his talk about fighting this pandemic is just that: talk," Cunningham tweeted Friday morning.

In a statement Friday, Tillis said he's "stressed the importance of mask wearing throughout this pandemic and have tried to lead by example on this issue, but last night I fell short of my own standard."

Cunningham and Tillis are facing in a tight race, with North Carolina playing a major role in Democrats' effort to take control of the Senate. Tillis didn't miss an opportunity in his Friday statement to make a swipe at Cunningham's tax record, which has been an attack point for both sides in the race.

"The difference between Cal Cunningham and I is that I can accept responsibility for my actions, while he lies and makes excuses for his, like how he has misused taxpayer dollars for his own personal gain and broke his promise not to raise taxes on hardworking North Carolinian," Tillis said.

Democratic state lawmakers pushed for an increase in sales tax to generate over $1 billion in more revenue back in 2001 — a vote that Tillis has used to portray Cunningham as a supporter of higher taxes, according to Raleigh's News and Observer.

Caitlin Oprysko contributed reporting.