Sen. Cory Gardner entered a self-quarantine after meeting with a constituent who tested positive for the coronavirus.

The Colorado Republican was notified on Tuesday that one of his constituents who visited his office in Washington, D.C., on March 11 tested positive for COVID-19. The senator decided that it would be best to isolate himself, despite not showing any symptoms.

"While I am not showing any symptoms at this time, I have made the decision to self-quarantine out of an abundance of caution with an effective date of March 11 at the recommendation of the Tri-County Health Department," Gardner announced on Tuesday.

Gardner was present at the Capitol on Tuesday and was photographed after speaking with reporters on his way to a Republican policy meeting with several lawmakers and Treasury Secretary Steven Mnuchin.

Several other senators have entered a self-quarantine after coming in contact with people who tested positive for the contagious illness, including Ted Cruz, Rick Scott, and Lindsey Graham . The coronavirus has an incubation period of at least 14 days, during which a person can be carrying the disease without presenting symptoms.

Gardner is facing one of the toughest Senate reelection bids in the nation. Many campaigns, including those of the Democratic presidential nominees, have shifted to virtual rallies and town hall events to curb the spread of the illness.