“We usually don’t take their phone calls because I think people want to help. But, again, we want to try to remain as independent as possible,” Osborn said in an interview after a campaign event in Lincoln, adding that he knows that if he’s elected he would need to “make alliances and make friends, and hopefully I can do that with both sides of the aisle.”

While Osborn aligns with Democrats on some issues, like abortion and labor rights, he’s closer to the GOP on things like border security and spending — his campaign has even started an affiliated “conservatives for Osborn” fundraising committee. He has vowed not to caucus with either party in the Senate.

That would set him apart from other Senate independents, like Angus King of Maine and Bernie Sanders of Vermont, who function as Democrats in all but name.

And in Nebraska, some Democrats are anxious that the party is getting its hopes up for a wild-card candidate who has spurned state and local party officials. Those Democrats are still smarting, in part, over Osborn’s decision to reject their endorsement earlier this year. While they ultimately decided not to field their own write-in candidate, they are unsure that the party’s base will enthusiastically show up for Osborn, even if Fischer is the only alternative.

“As each day goes by, the answer becomes less and less of a yes,” state Democratic Party Chair Jane Kleeb said, referring to whether Democratic voters in Nebraska can trust Osborn. “It’s like he’s crossed a line, and I just think it’s going to make partisan Dems uncomfortable — not wanting to have a Kyrsten Sinema among the ranks. … I think you’ll see some Democrats just simply not voting in that race.”

Former congressional candidate Ann Ashford — a Democrat backing Rep. Don Bacon (R-Neb.) in the state’s lone competitive House race — said she thought Osborn “tapped into the same folks that are interested in Trump,” but also that he “made a lot of Democrats really angry after the primary season after he said he would not caucus with them.”

“Some of the Democrats I’ve talked to, I think they’ll leave it blank,” Ashford said, referring to the spot on the ballot for the Senate race. She added that she’s staying out of that election and hasn’t donated to either campaign.

To win, Osborn will need to run the table with Democrats and independents, as well as get roughly 20 percent of Republican voters. And while Kleeb and other Democratic Party officials in Nebraska said they believed Osborn has a path to winning, losing the support of even a small slice of Democrats means he has to win more votes from Republicans.

The New York Times/Siena College poll had him winning 19 percent of registered Republican voters, but losing 9 percent of registered Democratic voters to Fischer. Five percent of both party bases said they didn’t know who they were voting for.

Part of what is fueling concerns from Democrats, is that Osborn has refused to say who he will vote for in the presidential election, even as it draws ever closer, and lingering questions about how his pledge to not caucus would work in practice.

He has presented his decision not to caucus with either party as a boon, since the majority is expected to be narrow regardless of which party wins control. Osborn argues that would give him significant leverage. Asked about the possibility that not caucusing instead makes it harder for him to get wins for his home state, since he doesn’t have a natural coalition, Osborn said: “That seems like a great problem to worry about [six] days from now.”

But his pledge to not caucus has emerged as a point of criticism from Republicans, who have dubbed Osborn a “Democrat in disguise.” They even seized on a fundraising text from an unaffiliated group run by a former Capitol Police officer and failed congressional candidate from Maryland that erroneously claimed Osborn would caucus with Democrats as evidence this week. (The group walked back its text and Osborn reiterated that he won’t caucus with Democrats.)

“You know, people have said to me: ‘What do you think of him saying he’s not going to caucus with Republicans or he’s not going to caucus with Democrats?’ And I said, ‘I think he needs a civics lesson’ because I just think that shows a lack of understanding,” Fischer told a group of Republican women during an event in Omaha.

Fischer is closely watching the signs of division between Osborn and some Democrats. She said in an interview after the event that “I’ve had Democrats reach out to me in the last 10 days. There’s something going on there.”

Not all Democrats are staying out of the race. One of the main super PACs supporting him has ties to the larger Democratic apparatus. (Super PACs cannot, by law, coordinate with candidates.) And Osborn has gotten support from some major Democratic donors, including Tom Steyer, as well as Rep. Don Beyer (D-Va.), according to FEC filings this week.

Osborn and his campaign said that it was unsurprising that Democrats would donate to him or outside super PACs supporting him, since they have a vested interest in defeating Fischer. But during an interview in Omaha, Osborn offered a warning if the anonymous donors fueling the outside spending come calling in favors later.

“If they do come calling ... I’m going to tell them to fuck off if they want me to do something for them,” Osborn said.