Former Colorado Gov. John Hickenlooper John HickenlooperGardner on court vacancy: Country needs to mourn Ginsburg 'before the politics begin' Vulnerable GOP incumbents embrace filling Supreme Court seat this year GOP campaign director: 'There's no doubt that Republicans will control the Senate' MORE (D) outraised Sen. Cory Gardner Cory Scott GardnerJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Gardner on court vacancy: Country needs to mourn Ginsburg 'before the politics begin' MORE (R) in the latest quarter in Colorado's high-profile Senate race.

Hickenlooper, who launched his senate campaign after dropping out of the White House race, raised more than $4 million in the first quarter of 2019, compared with about $2.4 million for Gardner, according to new filings with the Federal Election Commission. However, Hickenlooper has only about $4.9 million in the bank, while Gardner has $9.6 million cash on hand.

Hickenlooper announced his Senate campaign against Gardner in August after lackluster polling forced him out of the presidential race. He had previously ruled out a Senate run but was heavily courted by establishment Democrats who are eager to unseat Gardner.

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The former governor will have to face off against a host of other Democrats in Colorado’s primary scheduled for June but has the backing of the party’s Senate campaign arm and is the favorite to win.

Gardner is considered to be one of the most vulnerable Republican senators up for reelection next year, especially given Democratic presidential nominee Hillary Clinton Hillary Diane Rodham ClintonJeff Flake: Republicans 'should hold the same position' on SCOTUS vacancy as 2016 Momentum growing among Republicans for Supreme Court vote before Election Day Warning signs flash for Lindsey Graham in South Carolina MORE’s victory over Trump in Colorado in 2016.

The Cook Political Report, a nonpartisan election handicapper, rates the Colorado race as a “toss-up.”