John Hickenlooper has made the Democratic ballot for the U.S. Senate, state officials said Monday, making the the former two-term governor the first statewide candidate to land a spot in Colorado’s June primary.

Since he's already qualified for the ballot, Hickenlooper told Colorado Politics he plans to withdraw from the assembly process, which has been upended in recent days as the state scrambles to respond to the coronavirus outbreak.

“Today we received word that, thanks to the tremendous work of our team and grassroots volunteers, we have qualified for the U.S. Senate ballot,” Hickenlooper said in statement.

“Because we have already earned a place on the ballot and ongoing public health and safety concerns, we will be withdrawing from the assembly process at this time. This will allow us to direct our resources towards building a campaign ready to win the nomination in June and defeat Senator Gardner in November.”

Hickenlooper is one of nine Democrats seeking the nomination to run against Republican U.S. Sen. Cory Gardner, considered one of the most vulnerable senators on the ballot this year.

In order to qualify for the ballot, Hickenlooper's campaign had to turn in 1,500 valid signatures from registered Democrats in each of the state’s seven congressional districts, for a total of 10,500 signatures.

The Secretary of State's Office ruled valid 14,925 of the 17,439 signatures the Hickenlooper campaign submitted, making for an acceptance rate of roughly 86%.

Hickenlooper collected the most valid signatures in the Denver-based 1st Congressional District, with 2,220, but had more than 2,000 valid signatures in every district except the Aurora-based 6th Congressional District, were he had 1,979.

Three other Democratic U.S. Senate candidates are circulating petitions, which are due to election officials by end of day Tuesday — nonprofit leader Lorena Garcia, immigrant rights activist Michelle Ferrigno Warren and University of Denver professor David Goldfischer.

Psychologist and climate activists Diana Bray, who had been collecting signatures, announced Friday that she was suspending her petition drive due to public health risks surrounding the activity.

Hickenlooper's withdrawal from he assembly process leaves four Democrats seeking the ballot by that method: former state House Speaker Andrew Romanoff, scientist and educator Trish Zornio, former congressional candidate Stephany Rose Spaulding and tech entrepreneur Erik Underwood.

Romanoff won a U.S. Senate preference poll conducted at Democratic precinct caucuses on March 7 with 55% of the vote, ahead of Hickenlooper's 30%, with the others trailing further back.

In the non-binding poll, which was used to apportion delegates to county assemblies, Zornio had 6%, Spaulding had 5%, Underwood had 0.2%, and about 3% were uncommitted.

Romanoff on Monday said he would seek the support of the delegates who have been in Hickenlooper's corner.

“I respect John Hickenlooper, but I'm puzzled by his decision to run for a job he doesn't want, skip 19 debates to which he was invited and abandon Democratic assemblies he vowed to win," Romanoff said in a statement. "Colorado has a chance to replace Cory Gardner with a progressive champion. That's why we're asking everyone who caucused for Hick to join us instead."

Hickenlooper delegates elected at precinct caucuses are free to support any of the remaining candidates as the assembly process continues, potentially increasing the chances that at least two other Democrats will qualify for the June 30 primary ballot.

Hickenlooper delegates elected at precinct caucuses are free to support any of the remaining candidates as the assembly process continues, potentially increasing the chances that at least three Democrats will make the June 30 primary ballot.

In order to make the ballot by assembly, Senate candidates need the support of 30% of delegates to the state assembly, scheduled for April 18 in Denver.

During the process of verifying Hickenlooper's petitions, election officials at the Secretary of State's Office referred a circulator with a higher than usual rejection rate to the Colorado Attorney General's Office for investigation, the Hickenlooper campaign said.

In a letter to state officials obtained by Colorado Politics, the Hickenlooper campaign's attorney said the campaign learned about the referral on Friday and only discovered the same day that the circulator had been fired by the petition vendor on Feb. 23, four days after the Hickenlooper campaign submitted its petitions.

"Accordingly, while we understand that your office has found most signatures submitted by this circulator to be valid, the Campaign nonetheless requests that your office disregard all signature lines on the petition sections circulated by the individual in question," wrote Hickenlooper campaign attorneys Jonathan S. Berkon and Tyler J. Hagenbuch.

The campaign asked the Secretary of State's Office to discard the 75 signatures submitted by the circulator that had been ruled valid, leaving Hickenlooper with 14,925 total signatures, still well above the requirements.

Anyone planning to challenge the Hickenlooper campaign's petitions has five days to file an objection in Denver District Court after the secretary of state issues a statement of sufficiency.