Rep. John Boozman (R-Ark.) still holds a commanding lead over Sen. Blanche Lincoln (D-Ark.) in the latest poll in the Arkansas Senate race.

The new Rasmussen poll out Monday gives Boozman an 18-point lead over Lincoln--55 percent to 37 percent. Five percent of likely voters remain undecided while three percent chose another candidate.

The math remains daunting for Lincoln, but the latest numbers do show some slight movement toward the incumbent. This is the first Rasmussen survey where Boozman has dropped below 60 percent since this past spring.    

After surviving a tough primary challenge from Lt. Gov. Bill Halter (D) earlier this year, Lincoln is still struggling with her party's base. She has the support of just 72 percent of Democrats, while Boozman enjoys the support of a full 95 percent of Republicans.

While the national party is unlikely to spend any money on the race ahead of November, Lincoln is still getting support from one prominent Democrat--former President Bill Clinton. The former president penned a fundraising email to Lincoln supporters last week and is expected to campaign for her before Election Day. 

The poll surveyed 500 likely voters and has a margin of error of plus-or-minus 4.5 percentage points.