Sen. Claire McCaskill Claire Conner McCaskillDemocratic-linked group runs ads in Kansas GOP Senate primary Trump mocked for low attendance at rally Missouri county issues travel advisory for Lake of the Ozarks after Memorial Day parties MORE (D-Mo.) pitched unity during a recent fundraiser, urging supporters of Sen. Bernie Sanders Bernie SandersKenosha will be a good bellwether in 2020 Biden's fiscal program: What is the likely market impact? McConnell accuses Democrats of sowing division by 'downplaying progress' on election security MORE (I-Vt.) to be involved with her reelection campaign, according to audio posted by the state Republican Party.

"All of you who are Bernie supporters ... I need you. I want you. I want to talk to you. I want you to be part of our effort," McCaskill says in audio from the private event posted Thursday by the Missouri Republican Party.

"We can't get divided in a state like Missouri, or we're cooked," she added.

McCaskill's outreach to backers of Sanders — who ran a failed presidential campaign bid against Hillary Clinton Hillary Diane Rodham ClintonWhat Senate Republicans have said about election-year Supreme Court vacancies Bipartisan praise pours in after Ginsburg's death Trump carries on with rally, unaware of Ginsburg's death MORE for the Democratic nomination — came as she stressed why Democratic voters should stay united during her upcoming Senate primary.

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McCaskill said that in the Senate and on the campaign trail she is "working really hard to make sure our party stays together."

"I'm a little worried about a primary against me because I think the Republicans would want to return the favor," she said. "I think the Republicans might give a lot of money to one of my primary opponents doing a similar thing to what I did for Todd Akin."

McCaskill was referencing her campaign running ads during the three-way GOP primary in 2012 that touted Akin's conservative credentials in a bid to help him win his party's Senate nomination.

Less than two weeks after winning the GOP primary, Akin, a former Missouri congressman, sparked widespread ire when he told a local TV station that "if it's a legitimate rape, the female body has ways to try to shut that whole thing down."

Referring to her 2012 ads, McCaskill added during the fundraiser, "I know [Republicans would] love to return the favor, so I've got to be very careful about making sure we all stay together."

The fundraiser from earlier this week isn't the first time McCaskill has floated that she will likely have a primary challenger from the liberal wing of her party.

Referring to the progressive base, she told a St. Louis radio show last month that progressives could primary her because "they don't think I'm pure."

"And I may have a primary because there is, in our party now, some of the same kind of enthusiasm at the base that the Republican Party had with the Tea Party," she told the "The Mark Reardon Show."

McCaskill is one of 10 Democrats up for reelection in states carried by President Trump in November.

In addition to being targeted by GOP groups, who argue they are out of line with their states, red-state Democrats are also facing a wall of pressure from progressives to oppose Trump's nominees and agenda.

No Republican has formally said they will run against McCaskill, but the Democratic senator said she thinks Rep. Ann Wagner, who is close with Sen. Roy Blunt Roy Dean BluntCDC tells Congress it urgently needs billion for vaccine distribution On The Money: Trump undercuts GOP, calls for bigger COVID-19 relief package | Communities of color hit hardest financially by COVID-19 | Businesses, states pass on Trump payroll tax deferral Trump undercuts GOP, calls for bigger COVID-19 relief package MORE (R-Mo.), will be her opponent.