WAUSAU – Take a look at the Twitter feeds of U.S. Senate candidate Leah Vukmir and U.S. Rep. Sean Duffy, and you'll see the two marching in parades together and cheering each other's accomplishments.

It's probably not a coincidence.

Vukmir, a Republican, seeks to unseat Democratic U.S. Sen. Tammy Baldwin this November, and Duffy’s 7th Congressional District in northwestern Wisconsin looms large as a key component of her victory.

The district has become reliably Republican, particularly after statewide redistricting in 2011, but it is still made up of "independent-minded swing voters," said Mark Morgan, executive director for the Republican Party of Wisconsin.

"It’s definitely a critical area and a spot where we think we can continue to add to our coalition," Morgan said.

Fifty-eight percent of the district's voters backed Donald Trump in 2016, and the Republican Duffy defeated Democrat Mary Hoeft that year with nearly 62 percent of the vote. Yet GOP presidential candidate Mitt Romney only narrowly won the district in 2012 with 51 percent of the vote.

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Vukmir needs to carry the district convincingly if she's going to win November's statewide election, and Duffy's general popularity among his constituents helps explain why she has chosen to align with him, said Ed Miller, a political science professor at the University of Wisconsin-Stevens Point.

"If she loses that area or it’s pretty close in that area, she’s not going to win," Miller said.

Vukmir declined to discuss campaign strategy. But she said in a statement that Baldwin has "let us all down" and that she intends to continue to listen to Duffy's constituents.

"Sean and I share many similarities," Vukmir said. "As a nurse and a mom, I got into politics to make life better for my kids, and Sean is a dedicated dad who made it his mission to take the cares and concerns of Wisconsin’s families to Washington."

Vukmir still has work to do between now and November to make herself more known to voters. A Marquette University Law School Poll published this month showed the Democratic incumbent commanding an 11-point lead over Vukmir among likely voters. Meanwhile, 36 percent of registered voters couldn't offer an opinion on Vukmir.

That number is even greater in Duffy and U.S. Rep. Ron Kind's districts. Forty-seven percent of those polled by Marquette in western and northern Wisconsin weren't able to offer an opinion on Vukmir.

And as a state senator from Brookfield, Vukmir has never needed to interact with 7th District voters until now.

It's also worth noting the breakdown of the vote between Vukmir and Republican opponent Kevin Nicholson in the contentious August primary. While Vukmir secured the conservative Milwaukee suburbs and Dane County, Nicholson dominated central and northern Wisconsin.

In fact, every county in Duffy's district favored Nicholson over Vukmir. Although Nicholson voters are unlikely to embrace Baldwin, it's important for Vukmir to persuade his supporters to turn out and back her in November.

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Duffy's stamp of approval

Duffy endorsed Vukmir over Nicholson ahead of the primary, as did House Speaker Paul Ryan and U.S. Rep. Jim Sensenbrenner. But Duffy has followed that endorsement with vocal support, campaign appearances and frequent social media promotions.

In July, Duffy organized a rally for Vukmir in Wausau. The two have appeared together multiple times since, including at Labor Day parades in Wausau and Merrill. Duffy's campaign Twitter feed is full of tweets and retweets related to the Senate candidate.

Duffy makes regular appearances on Vukmir's Twitter account as well. Most recently, Vukmir applauded legislation introduced by Duffy that would remove federal protections for gray wolves under the Endangered Species Act — something Baldwin has also advocated.

Even before Duffy's endorsement, his wife, Rachel Campos-Duffy, was publicly supporting Vukmir. Campos-Duffy co-hosted a fundraiser for Vukmir with Tonette Walker, Gov. Scott Walker's wife, in March and nominated her for the Wisconsin GOP endorsement during a convention in May.

Duffy also appeared in a pre-primary ad on Vukmir's behalf, defending Vukmir's loyalty to Trump and calling ads against her "fake news." The ad ran after the conservative news site Breitbart published video of Vukmir in March 2016 saying Trump is "offensive to everyone." Trump tweeted in support of Vukmir after her primary win.

Although she didn't support Trump from the beginning, Vukmir has pledged repeatedly during her campaign that she will stand with him. Her loyalty to the president is yet another common thread between Vukmir and Duffy, who has been unwavering in his allegiance to Trump.

Duffy reiterated his support for Vukmir in a statement to USA TODAY NETWORK-Wisconsin, saying she fights for Wisconsin families and is willing to cut taxes and remove "unnecessary red tape" to help small businesses grow.

"She will beat Tammy Baldwin in November because Tammy tells us one thing, but then takes far-Left votes to raise taxes and healthcare costs, leave our southern border open, and grow Washington’s influence in our daily lives," he said.

Baldwin's campaign did not respond to a request for comment for this story.