RICHMOND — Peter Doran, a former Washington think tank executive and author, joined the crowded race for Virginia governor this week with a promise to phase out the state income tax.

“We’re going to zero percent,” Doran, 45, says in a campaign video. In an interview Wednesday, he said the state could wind up with more revenue without the tax because the change would fuel business and population growth.

Doran, who lives in Arlington County, is the sixth Republican to seek the party’s gubernatorial nomination. Five Democrats and an independent also are seeking to succeed Gov. Ralph Northam (D), who is prohibited by the state constitution from seeking back-to-back terms.

In addition to phasing out the income tax, Doran promises in the video to make Virginia the best state in the nation for schools, safety and jobs. In an interview, he described himself as a conservative on gun rights and abortion, but said he supports gay rights as long as there is no conflict with religious freedom.

“I don’t believe it’s the government’s business to get in between any two adults and tell them how to organize their lives,” he said. “But it is the duty of the governor and the government to protect religious freedom. So when a church or a synagogue or a temple does not perform same-sex marriages, that’s their religious right and it must be protected, too.”

Doran is the former president of the Center for European Policy Analysis, where he used to help former Soviet bloc countries rebuild after “the ravages of socialism,” according to his biography. An Arizona native, he has lived in Virginia since graduating from Georgetown University’s School of Foreign Service in 2006.

Doran is the author of “Breaking Rockefeller: The Incredible Story of the Ambitious Rivals who Toppled an Oil Empire,” a book recounting how two men managed to take down John D. Rockefeller’s monopoly. Kirkus Reviews calls it a “readable popular history told largely through the actions of swashbuckling tycoons.”

“I have always loved underdog stories, especially when the underdogs beat the big dogs,” Doran said in an interview.

But Doran said he does not see himself as an underdog in the governor’s race. While one of his Republican rivals has spent 30 years in the legislature, and two others have personal fortunes that will allow them to self-fund, Doran touts his lack of experience and wealth as assets.

“I might not be a multimillionaire, and I haven’t spent decades as a politician, but if you want to clean house in Richmond, if you want a governor who will work for you, then I’m your guy,” he says in the video, which was released Tuesday.

Others vying for the Republican nomination are state Sen. Amanda F. Chase (Chesterfield); Del. Kirk Cox (Colonial Heights), a former House speaker; retired Army colonel Sergio de la Peña; businessman Pete Snyder; and former Carlyle Group executive Glenn Youngkin.

The Democratic contenders are former delegate Jennifer D. Carroll Foy (Prince William), Del. Lee J. Carter (Manassas), Lt. Gov. Justin Fairfax, former governor Terry McAuliffe and state Sen. Jennifer L. McClellan (Richmond).

Also running is third-party candidate Princess Blanding, whose brother, Marcus-David Peters, was killed by Richmond police while he was experiencing a mental health crisis in 2018.

Republicans plan to choose their nominee May 1 at a party-run convention. Democrats will choose theirs in a June 8 primary.