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 passes college anti-Semitism bill Speculation and starting points: accreditation, a new administration and a new Congress The untold stories of the 2016 battle for the Senate 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 senator: Congress will ‘undo the damage’ from Obama Senate GOP to Obama: Stop issuing new rules Gardner's chief of staff tapped for Senate GOP campaign director 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.