*Editor's note: This story has been updated throughout.
Lt. Gov. Dan Patrick is getting a Democratic challenger for re-election in 2018.
The Texas Democratic Party said Thursday that Mike Collier is stepping down as finance chairman to start a campaign for lieutenant governor.
"Dan Patrick has proven he is unworthy of leading this great state," party Chairman Gilberto Hinojosa said in a statement Thursday. "I am proud to see a courageous Texan like Mike Collier put his name forward to serve."
In his own statement, Collier said he is "assembling a campaign team to run against Dan Patrick for Texas Lt. Governor." He added that he will make a formal announcement after touring the state and gauging support for his run.
"We need a Lt. Governor that brings Texans together, not an ideologue that chases headlines and drives us apart," Collier said.
Collier, an accountant from the Houston area, was the Democratic nominee for comptroller in 2014. He lost to Glenn Hegar by more than 20 points.
Collier faces a steep climb in his bid to unseat Patrick. The lieutenant governor has $13.6 million saved up for his re-election campaign.
Allen Blakemore, Patrick's chief strategist, said the lieutenant governor is currently focused on the legislative session, not the 2018 elections.
"After the session, he will his attention to reelection," Blakemore said in a statement. "I am supremely confident that the [lieutenant governor] will be reelected by a sizable margin and be back for another four years to keep Texas the very best place to live, work, and raise a family."
In a brief interview with The Texas Tribune after the announcement, Collier said he filed Thursday morning with the Texas Ethics Commission to run for lieutenant governor. He promised to run a "very policy-oriented, substantive campaign" involving many of the same issues he raised in his 2014 run.
While Texas Democrats are hopeful President Donald Trump's unpopularity will help them in 2018, Collier said he does not see Trump factoring into his race.
"I'm going to run against my opponent," Collier said. "My focus has been on the state of Texas."
"I love the state of Texas, and I need to do this," he added.