McCaskill said the poll made her “laugh out loud.”

The poll showed McCaskill in the lead with 48 percent support, while Akin has 38 percent.

A previous survey from liberal-leaning Public Policy Polling, conducted and released only one day after Akin’s controversial “legitimate rape” remark, showed the Missouri congressman with a 44 to 43 percent lead.

The GOP has put intense pressure on Akin to withdraw. GOP standard-bearer Mitt Romney on Tuesday personally called on Akin to stand down, and several Republicans senators have echoed that sentiment, as have prominent conservative bloggers.

McCaskill, meanwhile, has said it's not her place to say what Akin should do.

Democrats have been quick to push back against the poll, saying Rasmussen has a conservative bias and is in cahoots with GOP party leadership in trying to pressure Akin out of the race.

“Everyone knows that Rasmussen is a tool of the Republican establishment in Washington,” Democratic Senatorial Campaign Committee press secretary Shripal Shah told The Hill.