Sen. Claire McCaskill (D-Mo.), who's expected to be high on the list of GOP Senate targets in 2012, begins her race for reelection in a dead heat with Republican Sarah Steelman. 

Numbers from Democratic-leaning Public Policy Polling out Wednesday have McCaskill ahead of Steelman by just a single point — 45 percent to 44 percent. 

Steelman, a former state treasurer, officially jumped in the race against McCaskill Wednesday, but she could face a primary challenge from former Sen. Jim Talent (R-Mo.) or Lt. Gov. Peter Kinder (R). 

Both Republicans are better known than Steelman, and the poll gives both Talent and Kinder a slight edge over McCaskill. Talent leads the Democratic incumbent 47 percent to 45 percent in a hypothetical rematch. Kinder leads McCaskill 46 percent - 44 percent. 

One positive sign for McCaskill — independents split pretty evenly in all three hypothetical 2012 match-ups. A full 40 percent of self-identified independents favor McCaskill in a race against Steelman, who gets 37 percent of independents. In a McCaskill-Talent rematch, independents split 40-40. 

The poll surveyed 515 registered Missouri voters and has a margin of error of 4.3 percentage points. 

The Democratic Senatorial Campaign Committee already lobbed its first attack at Steelman Wednesday, labeling her a perennial candidate and "ultimate establishment insider." 

Steelman ran in the 2008 GOP gubernatorial primary but lost to establishment-backed Kenny Hulshof. Democrat Jay Nixon ultimately defeated Hulshof by almost 20 points in the general election.

—Sean J. Miller contributed to this post