Six women seeking the Democratic nomination for a Senate seat from Colorado are calling on the Democratic Senatorial Campaign Committee to reconsider its endorsement of former Colorado governor John Hickenlooper, who joined the crowded primary field last week after dropping out of the presidential race.

In a letter timed Monday to coincide with Women’s Equality Day, the women suggested that gender was a factor in the DSCC’s decision to back Hickenlooper and accused the national organization of trying to stage “a coronation.”

“All of us, like many women in Colorado and across the country, have seen well-qualified women passed over for male candidates in the workplace time and again,” they wrote. “Those of us who have run for office before have been told to ‘wait our turn’ and ‘don’t rock the boat’ more times than we care to mention. Now, the DSCC, by its endorsement, is implying that we should defer to a male candidate because you seem to believe he is ‘more electable.’ Colorado has never had a woman United States Senator and one has to wonder if circumstances such as this have contributed to that unfortunate outcome.”

The letter is signed by candidates Diana Bray, Lorena Garcia, Alice Madden, Stephany Rose Spaulding, Michelle Ferrigno and Warren Angela Williams.

In a statement, DSCC spokeswoman Lauren Passalacqua called Hickenlooper “far and away the strongest candidate” to defeat Sen. Cory Cardner (R-Colo.) next year, adding: “We’re proud to support him in his run for Senate.”

A recent poll conducted by Garin-Hart-Yang Research Group for an unnamed national organization showed Hickenlooper with a massive lead in a potential Democratic Senate primary, favored by 61 percent of likely voters. The nearest rival came in at 10 percent.

Since entering the race last week, Hickenlooper has picked up endorsements from several Colorado politicians, including several women.

One of them, state Sen. Kerry Donovan (D), said in a tweet last week that she is “proud to support” Hickenlooper, adding: “We need him in the Senate to bring people together, fight for our public lands, and work for Colorado families to bring down the cost of health care.”

Hickenlooper also won the backing this week of Ken Salazar, a former U.S. interior secretary and former Democratic senator from Colorado.

Nationally, Democrats view Colorado as a prime pickup opportunity next year in the Senate.

Gardner narrowly defeated Democratic incumbent Mark Udall in Colorado’s 2014 Senate race. After the 2018 midterm elections, he became the only Republican holding statewide elected office in Colorado.

Hickenlooper, who finished his tenure as governor at the beginning of the year, had struggled to translate his popularity in Colorado to the presidential race. In a field of more than 20 candidates, Hickenlooper remained stuck near the bottom of the pack, struggling to top 1 percent in most national polls.