But over the past four years he came to the conclusion that his moderate philosophies were more in line with those of the state's dominant party.
Russo, 51, of 10635 Trotter Drive, Hagerstown, officially changed his party registration in mid-May.
"I used to be a Republican that I felt moderate Democrats would feel comfortable voting for. Now I'm a Democrat I feel moderate Republicans would feel comfortable voting for," he said.
Russo is the first person to file in District 2B since the Maryland Court of Appeals revised the state's legislative redistricting map June 21, leaving Shank unopposed with a July 8 filing deadline.
Russo, who owns Russo's RX on Cannon Avenue, has served on the State Board of Pharmacy.
He earned bachelor's degrees in zoology and pharmacy from the University of Maryland. He has a juris doctor degree from University of Baltimore School of Law and a master's in business administration from Mount St. Mary's College in Emmitsburg, Md.
Russo criticized Shank and the rest of the majority-Republican Washington County Delegation for failing to lead effectively.
The city of Hagerstown hired its own lobbyist at one point rather than rely on local lawmakers for representation in Annapolis, he said.
A grassroots effort for charter government, which would shift power away from the delegation, is further proof that people are dissatisfied with the status quo, he said.
"That all goes to the question of effective leadership," he said.
Shank defended the delegation's accomplishments, citing legislation that reduced the county's water and sewer debt.
Shank said he is prepared to defend his record, but he also wants to hear what Russo stands for.
"My overall reaction is that if you're running for the House of Delegates you have to stand for something," Shank said.
Shank questioned Russo's party change.
"It sounds to me like he's more interested in finding a horse to ride on to get into elected office," Shank said.
Russo said Shank has taken a position against higher taxes, yet he proposed a building excise tax as an alternative to the Washington County Commissioners' transfer tax request last year. The delegation did not approve either tax increase.
Shank said it's fair to ask builders to help pay for the public roads, utilities and schools that will be required by their developments.
He said Russo supported impact fees on new development when he ran in 1998.