Former state Sen. Mike Johnston, 44, had led the field by raising $3.4 million since launching his campaign in January against Republican Sen. Cory Gardner. That's more than Hickenlooper raised in his presidential bid, but Johnston announced he was ending his campaign rather than battling against the best-known Democrat in the state.
"The nature of the campaign changes. Now you have to run a campaign that's 'Why not John Hickenlooper?'" Johnston said in an interview, noting that it'd be negative and expensive to do so. "I couldn't lead a campaign that was built on that."
Hickenlooper, 67, dropped his presidential bid last month and joined the Senate race after repeatedly saying he wasn't interested. He and his strategists had been hoping the former governor's universal name recognition and lingering warm feelings among Colorado Democrats would quickly winnow what they viewed as an unruly and unmanageable primary. Johnston is the first Democrat to step down — others running include former diplomat Dan Baer, former Colorado House leaders Alice Madden and Andrew Romanoff, state Sen. Angela Williams and former U.S. Attorney John Walsh.
To date, the field has reacted coldly to the entry of Hickenlooper, who is older than the rest of the field and governed as a moderate. Williams, seen as an ally of the governor's during his two terms, has warned "this won't be a coronation." Romanoff, who mounted an unsuccessful primary challenge in 2010 to Colorado's other Democratic senator, Michael Bennet, has complained that Washington Democrats are blackballing political firms that work for non-Hickenlooper candidates.
The battle is for the nomination against Gardner, seen as the most vulnerable GOP senator in the country because Colorado has become reliably Democratic terrain in the age of Trump. Republicans hope the Democratic primary becomes a circular firing squad, leading to a weakened nominee.
Johnston, who is friends with Hickenlooper, told the former governor about his decision Tuesday morning. He said he hadn't previously spoken to Hickenlooper since he entered the race two weeks ago. He also stopped short of an endorsement but warned that a nasty primary could be dangerous.
"It would really break a lot of long-standing coalitions in this state," Johnston said.