Former Colorado Gov. John Hickenlooper on Aug. 15 ended his longshot bid for the Democratic presidential nomination and said he may instead challenge one of the most vulnerable Senate Republicans in 2020.

In a video message , Hickenlooper said he had heard from many in his state urging him to enter the Senate race.

“They remind me how much is at stake for our country. And our state,'' he said. “I intend to give that some serious thought.''

Colorado's shift to the left could put Sen. Cory Gardner's seat in jeopardy for Republicans, and at least 10 Democrats have launched campaigns, setting up a competitive primary even before Hickenlooper, 67, makes a decision.

Hickenlooper became a leading figure in Colorado with his quirky, consensus-driven and unscripted approach to politics. He once jumped out of a plane to promote a ballot measure to increase state spending, and he won two statewide elections during years of Republican waves. He also was Denver's mayor.

He began his White House campaign in March, promising to unite the country. Instead, he quickly became a political punch line.

Founding a series of brewpubs made Hickenlooper a multimillionaire. But shortly before taking his first trip to Iowa as a presidential candidate, he balked on national television at calling himself a capitalist. Then, at a CNN town hall, he recounted how he once took his mother to see a pornographic movie.

With the campaign struggling to raise money, his staff urged Hickenlooper to instead challenge Gardner. But Hickenlooper stayed in and hired another group of aides in a last-ditch effort to turn around his campaign.

He positioned himself as a common-sense candidate who couldn't be labeled a “socialist” by Republicans. But Hickenlooper couldn't make his voice heard in the crowded Democratic field of about two dozen candidates.

It didn't help that, by Hickenlooper's own admission, he was a mediocre debater and an erratic public speaker. In the end, he could not scrape together enough money for many of his trademark quirky ads, only launching one in which avid beer drinkers toast Hickenlooper by comparing him to favorite brews.

“While this campaign didn't have the outcome we were hoping for, every moment has been worthwhile,” he tweeted.

Republicans seized on the meltdown of Hickenlooper's campaign as evidence the Democratic Party has become too radical.

“A two-term governor of a swing state and (hash)2020 presidential (hash)Democrat candidate who was booed for warning against his party's embrace of socialist policies has been forced out of the race,'' tweeted Kellyanne Conway, a top Trump aide, on Aug. 15. “Not left-wing enough...''

But Hickenlooper's own supporters attributed his failure partly to the persistence of former Vice President Joe Biden's strong position in the Democratic primary field. Hickenlooper launched his presidential bid presuming that the 76-year-old Biden would stumble, and the electorate would be hungry for another centrist with a track record of winning white moderates. But Biden remains in the lead in primary polls.

Hickenlooper softened his denials of interest in the Senate in recent weeks as his campaign finances dwindled and pressure increased from other Democrats. He met with Senate Minority Leader Chuck Schumer, who had urged Hickenlooper to challenge Gardner last year, shortly after a disappointing performance during the second Democratic debate in late July.

Hickenlooper started telling people he'd make a decision by the end of this week. Speculation reached a fever pitch after he hopped in a car driven by Sen. Michael Bennet, another presidential hopeful and Hickenlooper's former chief-of-staff in Denver city hall, for a long drive after a political event in Iowa last week.

Hickenlooper also recently met with Colorado's Democratic secretary of state, Jena Griswold, who was mulling a run against Gardner. Griswold recently announced she would not challenge Gardner. That decision led to widespread speculation among Colorado Democrats that Hickenlooper will eventually run. He has plenty of time to make up his mind — the primary is not until June 2020, and the former governor enjoys wide name recognition.

If he entered the Democratic primary, Hickenlooper would be “the absolute favorite,'' said Mike Stratton, a veteran Democratic strategist in Denver.

Hickenlooper would also be the oldest candidate in the Senate race, competing against politicians whose recent fundraising hauls have matched or exceeded the $1 million that Hickenlooper raised for his presidential bid in the second quarter of the year. Some of the other Senate challengers have said they don't intend to step aside even if the former governor runs.

“What I heard Gov. Hickenlooper tell everybody who asked is he wasn't cut out to be a senator and didn't want the job,'' said former Colorado House Speaker Andrew Romanoff, one of the primary contenders, in a radio interview.