(AP) COLUMBUS, Ohio - Sen. George Voinovich said Monday he won’t seek re-election in 2010, becoming the fourth Republican to make departure plans since the Democratic landslide in November.

Voinovich said in a statement that challenges facing Ohio and the country will require him to devote all of his energy to serving out his current term. Campaigning and fundraising would take time away from his work as a senator, he said.

"Those of us that have been given the honor to serve in these times must step up to the plate and put this country on a course that will see it through these harrowing times and make it strong and viable for the 21st century," Voinovich said.

Voinovich, 72, also said he wants to spend more time with his wife, children and grandchildren.

His announcement ends a career in Ohio politics.

Voinovich, one of the most popular Republican politicians in recent history in Ohio, served as mayor of Cleveland and was a two-term governor before his election to the Senate in 1998. He was considered a strong favorite for re-election if he had chosen to seek a third term in 2010.

In recent weeks, Republican Sens. Kit Bond of Missouri, Mel Martinez of Florida and Sam Brownback of Kansas have all announced plans to retire in 2010.

Voinovich’s decision was more bad news for Republicans. Democrats, who are just shy of a filibuster-proof margin in the Senate, will be on the offensive in the races for four open seats.

The decision by Voinovich sets in motion jockeying in both parties to replace Ohio’s senior senator.

Former U.S. Rep. Rob Portman of Cincinnati is figured to be a strong contender among Republicans. A message seeking comment was left Monday at Portman’s law office.

Lt. Gov. Lee Fisher and U.S. Reps. Tim Ryan and Zack Space are potential Democratic candidates.

Voinovich was a strong supporter of a proposed federal bailout for the auto industry, which put him at odds with a significant portion of the GOP caucus. He released a strong statement following the failure of the bailout, saying the politics of his colleagues had "failed" the auto industry.

He has been considered a political moderate.

Democrats had viewed Voinovich as vulnerable, given a political climate that has drastically shifted in Democrats’ favor in recent years.