Akin, who has been asked to withdraw from the race by high-profile Republicans across the spectrum, has steadfastly refused to cave to the demands. He still technically has until Sept. 25 to have his name removed from the ballot.
In a St. Louis Post-Dispatch/News 4 poll released Sunday, McCaskill led Akin 50 percent to 41 percent.
Utah Democratic Party Chairman Jim Dabakis said that might have been why McCaskill's event was closed to the press.
"She still doesn't necessarily know he [Akin] will be her opponent," Dabakis said. "It's a bit of a strange situation."
McCaskill campaign spokeswoman Caitlin Legacki said it's "a standing policy" to not have press at fundraisers.
Dabakis delivered remarks at the fundraiser attended by about 100 people who were required to donate a minimum of $100 and said McCaskill focused on her role as a moderate senator fighting for the middle class.
"She's a blue senator in a red state," Dabakis said. "She is a moderate and a centrist."
Several Democrats who attended said McCaskill didn't talk much about Akin, but she did manage to deliver a zinger during a 15-minute question-and-answer period. The senator was asked how Akin managed to get onto the House Committee on Science.
Her retort was a rhetorical question, according to Deb Henry, campaign manager for Josie Valdez, who is running for state senate.
"McCaskill said, 'How did Michele Bachmann get onto the Intelligence Committee?'" Henry said.
The fundraiser, organized by Blaze Wharton, former Utah Democratic Party executive director, also featured and benefitted Sen. Jon Tester, D-Mont. Tester is running against Montana's lone congressman, Republican Denny Rehberg, a rancher and businessman.