COLUMBUS, Ohio--Two more Ohio Democrats have filed paperwork to run for statewide office in 2018: former Cincinnati mayoral candidate Rob Richardson Jr. for treasurer and ex-U.S. Rep. Zack Space for state auditor.

Richardson, a labor attorney, came in third during the May 2 Cincinnati mayoral primary with slightly more than 20 percent of the vote. It was his first run for political office, though he served nine years on the University of Cincinnati board of trustees - including one year as chair.

His father, Robert Richardson Sr., is a national labor leader and head of the Cincinnati NAACP.

The younger Richardson didn't return a phone call seeking comment Monday. But he told the Cincinnati Enquirer that Democratic Party officials approached him about exploring a run.

"I wasn't actually looking for it," Richardson told the newspaper. "I was in reflection mode, ready to get back to the private sector."

Richardson is the first Democrat to enter the race for treasurer. The current treasurer, Republican Josh Mandel, is term-limited and is running for U.S. Senate next year.

Two Republicans have launched campaigns for treasurer: Franklin County Auditor Clarence Mingo and state Rep. Robert Sprague of Findlay.

Space, a 56-year-old from Dover, represented Ohio's 18th congressional district for two terms until he was unseated by Republican Bob Gibbs in 2010. He now works for the prominent Columbus law firm Vorys, Sater, Seymour and Pease.

Republican Keith Faber, a state representative and former Ohio Senate president from Mercer County, is also seeking the auditor's job. Term-limited GOP incumbent Dave Yost is running for attorney general.

One of five statewide executive elected offices in Ohio, the state auditor is responsible for auditing public bodies, investigating fraud in public agencies, and providing financial services to local governments, among other duties.

Space was not immediately available for comment Monday.