Interior Secretary Ken Salazar is back in his home state Sunday to campaign for Rep. Betsy Markey (D-Colo.), a former employee of Salazar’s who is also one of the more vulnerable Democratic incumbents in this midterm election.

Salazar was scheduled to participate in an event at a park in Greeley, Colo. “Rain or shine, my rally with Ken Salazar will go on!” Markey tweeted Sunday. It was scheduled from 11:30 a.m. to 1 p.m. MST.

Salazar visited the same park in Markey's district two years ago to campaign for her before she unseated three-term Republican Rep. Marilyn Musgrave. Salazar in August also campaigned for another embattled Democratic incumbent from Colorado up for reelection, Sen. Michael BennetMichael BennetSenate advances Trump's Commerce pick Senate Dems move to nix Trump's deportation order Senators to Trump: We support additional Iran sanctions MORE.

Markey was a district representative for Salazar when he was a Democratic U.S. senator from Colorado.

She is facing a stiff challenge from Republican Cory GardnerCory GardnerGOP loses top Senate contenders Graham: Ryan tax plan won’t get 10 votes in the Senate The Hill's 12:30 Report MORE, the minority whip in the Colorado General Assembly.

According to a recent poll commissioned by The Hill, Gardner led Markey by only 3 points in the Republican-leaning district — within the poll’s margin of error — with 14 percent of likely voters undecided.