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 BennetTrump's FDA nominee clears key Senate committee Dems knock Trump on Earth Day Dem pushed plan for both sides to admit to abusing Senate rules: report 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 GardnerOvernight Defense: Commander calls North Korea crisis 'worst' he's seen | Trump signs VA order | Dems push Trump to fill national security posts Senators get North Korea briefing in unusual WH visit A Vandenberg movement in Congress 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.