Democratic U.S. Senate candidate Andrew Romanoff on Monday challenged John Hickenlooper to a series of seven debates before voters pick a nominee to challenge U.S. Sen. Cory Gardner, the Republican incumbent, in Colorado’s June 30 primary.

With mail ballots set to go out to most state voters starting on June 9, that would amount to one debate per week before voting starts.

“I will strongly support the Democratic nominee in this race. But that doesn’t mean we duck and cover in the meantime,” Romanoff, a former state House speaker, said in a fundraising email sent to his supporters on Monday. “Ballots arrive in just seven weeks, and voters deserve to hear from both Democratic candidates before then. That’s why I’m challenging John Hickenlooper to debate.”

A spokesman for the Hickenlooper campaign told Colorado Politics that the former two-term governor is willing to debate his primary opponent but wouldn’t say how many times.

“John has been campaigning all across Colorado for the past eight months, holding events in 54 counties already,” Ammar Moussa, the Hickenlooper campaign’s press secretary, said in a written statement. “He looks forward to meeting with more voters and participating in more forums and debates throughout this campaign.”

Hickenlooper succeeded in petitioning onto the ballot last month. On Saturday, Romanoff joined him in the primary after receiving 86% of the delegate vote at the Democrats’ state assembly, making him the only candidate with enough support to qualify.

Another candidate, nonprofit executive Lorena Garcia, learned Friday from the Colorado Secretary of State’s Office that she didn’t submit enough valid petition signatures to make the ballot but has vowed to challenge the ruling in court.

In an email sent by Romanoff to Hickenlooper and obtained by Colorado Politics, Romanoff taunted his opponent for skipping numerous candidate forums in recent months.

“The voters deserve to hear from both of us on the same (virtual) stage” before ballots go in the mail, Romanoff wrote. “Your absence from 19 candidate forums throughout this campaign made that difficult. I’m sure your schedule – like mine! – is a little clearer now … . Let’s give the people of Colorado a chance to make an informed decision.”

Endorsed by the Democratic Senatorial Campaign Committee after the group helped recruit him into the primary, Hickenlooper has taken heat in recent months from primary challengers and some progressive organizations for declining to attend forums devoted to climate change and other issues. He participated in most of the forums sponsored by the Colorado Democratic Party that were held in late 2019.

The Colorado race could be among the country’s most expensive and hard-fought this year, with control of the Senate potentially at stake.

While Romanoff has demonstrated that he has strong support among the Democrats’ left-leaning activist base, Hickenlooper raised nearly 10 times as much money in the most recent fundraising quarter and outpaces Romanoff in name recognition and voter approval, according to the scant publicly available polling in the race.