Former Colorado Gov. John Hickenlooper ended his presidential campaign on Thursday and said he was giving “serious thought” to a Senate bid.

“Today, I’m ending my campaign for president,” Hickenlooper announced in a video posted to Twitter. “But I will never stop believing that America can only move forward when we work together.”

Hickenlooper’s expected departure from the race was reported by NBC News on Wednesday night. He had struggled to garner substantial support in the crowded Democratic primary field and appeared unlikely to make the cut for September’s Democratic debate.

“I’m also proud of the campaign we ran,” Hickenlooper said. “I want to thank each of you.”

“People want to know what comes next for me,” the former governor and mayor of Denver added. “I’ve heard from so many Coloradans who want me to run for the United States Senate. They remind me how much is at stake for our country and our state. I intend to give that some serious thought.”

Recent polls showed Hickenlooper leading Cory Gardner, the Republican incumbent, as well as other Democratic candidates. Gardner, in his first term representing a state that went for Democratic presidential nominee Hillary Clinton in 2016, is one of the most vulnerable GOP senators up for re-election in 2020.

This month, NBC affiliate KUSA of Denver reported that a Colorado political consultant had reserved several “Hickenlooper for Senate” web addresses.