KNOXVILLE, Tennessee — U.S. Rep. Tim Burchett has joined the chorus of concerned citizens urging the public to help find a man with dementia missing since Nov. 17.

"My family and I are praying for Mr. Harrison and his family, as well as the dedicated law enforcement officers and members of our community working to bring Mr. Harrison back to safety," a statement Wednesday from the Knoxville congressman reads. "Before heading out to the grocery store, shopping for holiday gifts or running errands, please take a look at the photo of Mr. Harrison. Remember his appearance and keep him in mind as you go about your day."

Jack Harrison, 77, was last seen the night of Nov. 17 on video at the gas pump parking lot outside the Walmart east of Norris Freeway in Halls.

He'd been with family at the store, became separated and went outside.

RELATED: 16 days later, search continues for missing Knox Co. man with dementia

RELATED: "No actual sightings" of man missing for 10 days in Halls, sheriff says

RELATED: Protecting loved ones who suffer from memory loss conditions

RELATED: Sheriff: Please check your barns, vehicles, creeks for signs of missing Halls man

According to the Knox County Sheriff's Office, Harrison was wearing blue jeans, a multicolored polo shirt and a brown jacket. He may have been wearing a baseball hat with what appeared to be a Denver Broncos emblem on it.

search for jack harrison
Grace King

Family, friends and the Sheriff's Office have searched repeatedly for him without luck.

There have been no confirmed sightings of him since he disappeared, according to Sheriff Tom Spangler.

"We are grateful to the media, the public and Congressman Burchett for their assistance in the ongoing search efforts to bring Mr. Harrison home," Spangler said in a news release.

Spangler previously has asked the public to search area barns, outbuildings, creeks and any empty vehicles on their property for signs of Harrison's whereabouts.

If you think you've spotted Harrison, you should call 911. If  you have information that could help detectives, call the KCSO at 865-215-2243.