Wisconsin has proven to be an odd state in the 2016 primary season.

It's seen as a blue state, as it hasn't voted for a Republican presidential candidate since 1984, but it currently has a well-known Republican governor, the Republican speaker of the House — a star of the party — and a Republican senator. And in the past two presidential races, the Badger State was one of the states with the closest outcomes in the country.

It might more accurately now be described as a deeply purple state. And thanks to its position as being a standalone primary amid many multiple-state contests — and the fact that there won't be another major state primary until April 19 (Democrats have a contest in Wyoming on Saturday) — people will be analyzing Wisconsin to death. I'm not different.

Voters in the state did not choose the front-runners of either party. Instead, Republicans chose Texas Sen. Ted Cruz, and Democrats chose Vermont Sen. Bernie Sanders. On the Democratic side, Sanders ran away with 57 percent of the vote to Clinton's 43 percent. Despite Clinton getting a large percentage of the vote, she won only a single county — Milwaukee.

Wisconsin Democratic Sen. Tammy Baldwin endorsed Hillary Clinton last summer. But former Democratic Sen. Russ Feingold, who is running against Republican incumbent Ron Johnson for his old seat, hasn't made any official endorsements.

It makes sense for Feingold to hold back on an endorsement. He doesn't want to jump on the Clinton train because, clearly, Wisconsin Democrats don't see her as their preferred option. And being locked in a close race with Johnson (RealClearPolitics has Feingold up 3.5 points), endorsing a candidate voters of his state don't like would be politically toxic.

Some — including the Capital Times of Madison, Wis. — have shown similarities between Feingold and Sanders. Feingold's political action committee donated to Sanders' presidential campaign in January 2015 (though an aide to Feingold's campaign said no one should read into that year-old donation). Several reliably progressive groups have endorsed Sanders and Feingold, including MoveOn.Org and Democracy for America.

One could speculate that Feingold might be closer to Sanders than to Clinton, and one couldn't blame him considering the former secretary of state's poor performance in the Badger State on Tuesday night. Endorsing Clinton would also be an easy way for Johnson's campaign to tag Feingold as a career politician, just like Clinton.

This is exactly the tactic the Johnson campaign is already taking, evidenced by the following response to the Washington Examiner.

"Wisconsinites made clear on Tuesday they don't trust Hillary Clinton and they don't think she will get our country back on the right track," said Johnson Campaign Manager Betsy Ankney. "Like Sen. Feingold, she's a career politician who will say anything, even if it's not true, just to stay in power."

Then again, endorsing Sanders would allow the Johnson campaign to tag him as a socialist.

Not endorsing anyone in the primary would continue a tradition for Feingold. In 2008, he made no endorsement, but told media outlets after he voted that he cast his ballot for then-Sen. Barack Obama.

Johnson has had his own issues with endorsements. He was previously a supporter of Wisconsin Gov. Scott Walker's presidential campaign (naturally), but after Walker dropped out, Johnson said he would support the Republican nominee, whomever that might be. This, of course, drew ire from Feingold, who knocked Johnson for not denouncing Republican front-runner Donald Trump's outlandish comments and campaign.

Obviously, endorsing Trump would be at least as toxic to Johnson at this stage of the game as Feingold endorsing Clinton, as Trump also lost the state by a large margin. But seeing as how Democrats had a much smaller presidential field to begin with, Feingold's unwillingness to endorse speaks volumes to Clinton's vulnerability in the Badger State.

Feingold's campaign did not respond to a Washington Examiner inquiry. This post will be updated when and if they respond.

Ashe Schow is a commentary writer for the Washington Examiner.