Former Governor John Hickenlooper of Colorado dropped out of the 2020 Democratic presidential primary on Thursday after struggling to gain traction in the crowded field.

"Today, I am ending my campaign for president, but I will never stop believing that America can only move forward when we only work together," Hickenlooper said in a Thursday video.

As Hickenlooper's presidential campaign fizzled out, several Colorado-based groups began publicly calling on him to challenge vulnerable GOP Senator Cory Gardner, who is up for re-election in 2020.

Hickenlooper, 66, was highly popular as governor for two terms. Before that, he served as mayor of Denver, a nonpartisan position, and was a successful businessman and brewery owner.

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Former Governor John Hickenlooper of Colorado dropped out of the 2020 Democratic presidential primary on Thursday after struggling to gain traction in the crowded field.

Hickenlooper, who entered the race in March, said in a video message on Thursday, "I ran for president because this country is being ripped apart by partisan politics and games while our biggest problems go unsolved. Today, I am ending my campaign for president, but I will never stop believing that America can only move forward when we only work together."

The former governor did not definitively say, however, say whether or not he would run for Senate.

"People want to know what comes next for me. I've heard from so many Coloradans who want me to run for the United States Senate," he said in the video, adding that he intended "to give that some serious thought."

As Hickenlooper's presidential campaign fizzled out, several Colorado-based groups began publicly calling on him to challenge vulnerable GOP Senator Cory Gardner, who is up for re-election in 2020.

While multiple Colorado Democrats are already running for Senate, preliminary polling indicates Hickenlooper would dominate the Democratic primary field.

The 314 Action Fund, a group trying to draft Hickenlooper to run for Senate said in a Wednesday statement to INSIDER, "there are two dozen Democrats vying to take on President Trump, but only one with the record and the vision to get Cory Gardner out of the U.S. Senate."

Read INSIDER's in-depth profile of John Hickenlooper from March 2019

Hickenlooper, 66, was highly popular as governor for two terms before being succeeded by Democratic Gov. Jared Polis. Before that, he served as mayor of Denver, a nonpartisan position, and was a successful businessman who founded Colorado's first brewery pub, helping bring jobs and economic development to Denver.

In February, several sources close to Hickenlooper told INSIDER they believed the former governor could successfully carve out a lane as a progressive but pragmatic and business-friendly dealmaker with a track record of concrete accomplishments.

But Hickenlooper, like many of the other relatively centrist candidates in the Democratic primary field, struggled to compete in the shadow of former Vice President Joe Biden and failed to break through 1% in the polls or raise enough money to stay viable.

And at his first CNN town hall in March, Hickenlooper set the tone with some unfortunate gaffes, including recounting a story of accidentally seeing the pornographic film "Deep Throat" with his mother and when asked if he would commit to selecting a female running mate, wondering why female candidates weren't asked if they would pick a male running mate.