Ohio Lt. Gov. Lee Fisher has filed paperwork to explore a Senate bid, making him the first Democrat to take a concrete step toward running for the open seat in 2010.

Fisher spokeswoman Lauren Goode said the filing was an indication that Fisher was “very serious” about running to succeed retiring Sen. George Voinovich (R-Ohio).

Fisher would be the first Democratic candidate to enter the race, although a handful of other Buckeye State elected officials are looking at a bid. Gov. Ted Strickland (D), however, told a local newspaper last week that he would support Fisher over other Democrats, including Secretary of State Jennifer Brunner and Reps. Tim Ryan and Zack Space.

Goode would not a discuss a timeline for the Fisher’s final decision.

“He hasn’t put a specific a date on it, but my sense is that we’ll have a decision in the next couple weeks,” she said.

Republican support has coalesced behind former Rep. Rob Portman (R), although state Auditor Mary Taylor (R) is mentioned as possibly looking at the race.