But the last few weeks have not been kind to Strickland—a taste the GOP gave him of what awaited if he decided to run. Republicans, and even some former supporters, have called into question his decades-long record as a moderate, pro-coal, pro-gun Democrat with unusually deep support in certain parts of the state.
Strickland spent the past year working for a liberal, Washington-based think tank that advocates for clean energy and stricter gun-control measures. Strickland stepped down from his role at the Center for American Progress two weeks ago, and in one of his last official actions, he advocated for changes in federal coal policy to help struggling Appalachian mining communities. But a spokesman from the United Mine Workers of America, which has been one of Strickland's biggest supporters in past campaigns, said his group's support was far from certain, one sign of how Strickland's career since losing reelection in 2010 could damage his Senate prospects.
"It would be some time before we make a decision, if we get involved at all," United Mine Workers spokesman Phil Smith said. "We supported Governor Strickland in the past, but that's—we're going to have to see how our members want to deal with that as we move forward."
Still, Strickland is considered a top-tier candidate who could help put a tough race in play. President Obama carried Ohio twice, but the nation's quintessential swing state often proves tricky for both parties simultaneously, and Portman started 2015 with solid approval ratings and millions of dollars in the bank. Democrats may still need to rely on a strong presidential performance to pull the state away from Portman, but many in the party believe Strickland's candidacy further clears the path toward retaking the Senate.
Democrats need four seats to win back the chamber if their party also wins the White House, and much of their opportunity is concentrated in the seven Republican-held seats Obama won in both 2008 and 2012, beginning with three GOP senators in especially blue-leaning presidential states: Wisconsin's Ron Johnson, Illinois's Mark Kirk, and Pennsylvania's Pat Toomey. But none of the three look like easy outs, and the map gets tougher from there, in swing states like Florida, New Hampshire, and North Carolina that are more tightly divided politically.
Democrats are focused on landing top recruits, like Strickland, in each of those races as a crucial first step toward putting as many states as possible in play next year.
The Ohio race also underlines one of Democrats' biggest challenges thus far. Widespread losses in 2010 and 2014, plus GOP-controlled redistricting processes that eliminated many blue-leaning swing seats in Congress and state legislatures, have shrunk the Democratic bench mightily in many states. Strickland isn't the only party veteran getting a call-up to help fill that void. Former Sen. Russ Feingold is widely expected to be Johnson's opponent in Wisconsin next year, while some Democrats also hope former Sen. Kay Hagan bounces back from her 2014 loss by taking on GOP Sen. Richard Burr in North Carolina. And while Democrats insist they are top-notch candidates who, like Strickland, have proven abilities and only lost in terribly unfavorable election years, Republicans are eager to reopen the books on people they have already defeated once.
Portman's statement after Strickland's announcement, in which he welcomed the former governor "back to Ohio," said it all. "Ohio families deserve a senator who will fight for their future and they can't afford to go backward with Governor Strickland," Portman said.
This story has been updated with additional information.