AUSTIN — The man who sued to overturn Texas' ban on gay marriage will run for the state Senate as a Democrat, vying for the seat that represents much of Collin County.

Mark Phariss told The Dallas Morning News he decided to run after seeing Democrats win in other Republican strongholds, like Virginia and Alabama.

"When I was accepting the fact that I was gay, there were two things I kind of thought I had to give up: one, getting married, and two, running for political office," Phariss said Tuesday. "I need to quit assuming what people will think. I need to allow them the choice."

Phariss, a business lawyer based in Plano, and his longtime partner, Victor Holmes, an Air Force veteran, were among four people who sued Texas in 2013 over its ban on same-sex marriage. Their case was in progress when the U.S. Supreme Court extended the right to marry to all same-sex couples in June 2015.

Phariss and Holmes wed just months later. Between the day the two met and the day they could legally call each other "husband," 18 years had passed.

Phariss will first face Plano resident and engineer Brian Chaput in the Democratic primary on March 6. Whoever wins that race will proceed to the November general election against either Angela Paxton or Phillip Huffines, who are duking it out for the GOP nomination.

Paxton is the wife of Attorney General Ken Paxton, an outspoken opponent of same-sex marriage, and Huffines is the twin brother of Don Huffines, a Republican senator who represents Dallas. If Phariss were to advance to the general election and win, he'd be Texas' first openly gay state senator.

The Senate District 8 seat opened up when GOP incumbent Van Taylor decided to run for Congress. The district encompasses much of Collin County, including parts of Allen, Frisco, McKinney, Plano and Richardson.

In a news release announcing his candidacy, Phariss touted the endorsements of former Housing Secretary Julián Castro and Jim Obergefell, the man whose suit overturned bans on gay marriage nationwide. Phariss said Donald Trump's 8.6-percentage-point win over Hillary Clinton in the district showed it could be time to turn the area blue.

Phariss also promised to bring "common-sense solutions" to the Capitol.

"The Legislature needs to refocus its attention on our state's important issues — like attracting good jobs and reducing traffic congestion — and avoid divisive policies that hurt our state's reputation and competitiveness, like 'show me your papers' laws," Phariss said. "Most importantly, the Legislature needs to fund our children's educational programs."

In a dig against Texas' bathroom bill — a failed attempt to segregate bathrooms by birth sex — Phariss added, "Classrooms, not bathrooms, will determine our children's and our state's future."

A longtime Democrat and staple in the LGBT rights community, Phariss has also spoken of his old friendship with Republican Gov. Greg. Abbott. The two attended Vanderbilt University law school together, and Phariss sat with Abbott's family in the hospital after he was paralyzed by a falling tree in 1984.

When asked about the views on LGBT rights of GOP leaders in Texas, as well as his opponents, Phariss said he thought the state's leadership was out of step with its citizens, whose "hearts are as big and wide" as Texas.

"I'm absolutely gay. There is no way to hide that," Phariss said. "But I'm running as a Texan, and I will absolutely represent every constituent in my district if I win. So even those who vote against me — even those who vote against me because I'm gay, I will want to listen to them and represent them."

"Our marriage equality case was all about saying we are just like everyone else," he added.

"I'm just like everyone else. That's what I want people to vote for me on."