This article is from the archive of our partner National Journal

To most Democratic and Republican leaders in Wisconsin, it's no longer a question of if Russ Feingold runs for Senate—it's a question of when he'll formally enter the race.

The latest round of speculation over Feingold's future started Thursday, when the Huffington Post reported that the former three-term senator was scheduled to deliver his final speech next week as a member of the State Department, where he's served since 2013 as a special envoy to central Africa.

If Feingold's departure is imminent, that comes as no surprise in Wisconsin, where political insiders have believed for months that Feingold would return to take on GOP Sen. Ron Johnson next year in a repeat of their 2010 matchup. "The general assumption and hope is that Russ Feingold does run for Senate in 2016," said Mike Tate, chairman of the Wisconsin Democratic Party.

Feingold, Tate added, is the "strongest candidate to take on Ron Johnson in 2016."

Feingold's anticipated return effectively froze other competitors for the Democratic Senate nomination, all of whom are wary of taking on a liberal favorite in a primary. Even though the Hatch Act, a federal law that forbids executive branch employees from political activity, prevented Feingold from publicly lobbying for the job, most understood that his return was likely. As Wisconsin-based lobbyist and GOP strategist Brandon Scholz put it, Feingold's impending campaign was "the worst kept secret in Wisconsin."

"If he didn't run, there would be greater surprise than if he did," Scholz said.

A matchup against Johnson would be one of the biggest showdowns of 2016, a virtual must-win race for Democrats desperate to retake the Senate and a chance for Republicans to show that they can win a blue-state seat even in less-favorable presidential election years. Johnson was elected in the tea party wave of 2010, and though he's tried to temper his image as a conservative firebrand, his campaign had just over $600,000 in the bank to start to the year. The tea-party persona, weak fundraising, and unfavorable turnout patters in a presidential year explain, at least in part, why many Republican strategists consider Johnson their party's most vulnerable Senate incumbent next year.

"If Feingold were to run, he'd clear the Democratic field and by all measures be considered the front-runner over the incumbent," said Thad Nation, a Democratic strategist and Wisconsin political veteran.

Of course, defeating an incumbent is never easy. Feingold frustrated many Democrats during his last campaign when he blocked the Democratic Senatorial Campaign Committee from spending money on TV ads in his race, and the architect of the McCain-Feingold campaign finance regulations also declined to authorize the creation of a super PAC to work on his behalf. (The concept of super PACs had been made legal only earlier that year.) Democrats are hopeful that, in 2016, Feingold will yield to third-party efforts.

"Listen, he's a smart guy," said one Democratic insider, who wouldn't speak candidly about campaign strategy without anonymity. "He understands in this post-Citizens, post-McCutcheon world, he can't fight with one hand tied behind his back."

Jon Tester, chairman of the Democratic Senatorial Campaign Committee, also suggested Feingold had a change of heart in an interview this month with The Hill.

Feingold also will have to persuade voters—at least those who turned out in a midterm election—to support a candidate they threw out of office six years ago. And many of the legislative votes that hurt his candidacy then, like his support of Obamacare, could still hurt him during a campaign next year.

"He's got a record of being fully supportive of a big, intrusive, controlling federal government, and I would say right now that that doesn't sell very well," Johnson said in an interview with the National Review.

Most Democrats expect Feingold to formally become a candidate by the late spring or early summer—though they stress no timeline is yet certain.

"I would think by the summertime, it will be clear that Russ is out there traveling the state," said the Democratic insider.

This article is from the archive of our partner National Journal.

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