Sen. Claire McCaskill (D., Mo.) confessed to a group of voters that her reelection campaign has "struggled with volunteers" and that her campaign offices "feel depressing," according to video captured by the Republican National Committee.

"The difference between a campaign office that's vibrant and full and one that isn't is volunteers," McCaskill said during an event last week with the Heartland Black Chamber of Commerce in St. Louis. "I will tell you, we have struggled with volunteers in the first month."

McCaskill went on to detail how much the campaign relies on volunteers, saying it has 55 employees staffing 41 offices across the state. She stressed the need for volunteers in predominantly African-American communities like the nearby city of Ferguson, where she has struggled to make inroads.

"I'm not going to sugarcoat it, we need more volunteers in Ferguson," McCaskill said. "We need more people showing up, the office is open, you can show up and they'll give you ideas about what you can do to help."

"That's the difference between a campaign office that feels like it's doing something and one that feels depressing," she said.

McCaskill's campaign didn't respond to a request for comment on the plea for volunteers.