A new Rasmussen Reports poll (11/18; 570 AZ registered Republican voters) is likely causing heartburn for Republican former presidential nominee John McCain. Back in Arizona, the senator only leads former Rep. J.D. Hayworth 45-43% in a hypothetical 2010 Republican senatorial primary match-up.

Hayworth, now a Phoenix radio talk show host since losing his congressional seat to Democrat Harry Mitchell in 2006, has not yet launched a challenge to McCain, but is openly considering the possibility of running.

Sen. McCain has long been at odds with the more conservative wing of the Republican Party over a myriad of issues. His co-authorship of the McCain-Feingold campaign finance legislation that weakened the national political parties and banned the solicitation of non-federal funds by such committees, federal office holders, and candidates, has done extensive damage to the GOP and significantly contributed to its recent downward electoral spiral.

McCain's home state presidential primary performance provides an illustrative example that the veteran lawmaker has significant political weaknesses. Though he easily won the Arizona primary back in 2008, he did so with considerably less than an absolute majority. In fact, even though no other candidate was actively campaigning in Arizona, 53% of Grand Canyon State Republican voters still chose a presidential contender other than their own Senator.

While it appears almost unfathomable that McCain’s home state party would turn him out of office just two years after he was the national Republican standard bearer, we must remember that a similar rejection has already occurred. Connecticut Democrats denied Sen. Joe Lieberman – the 2000 Democratic Vice-Presidential nominee and presidential candidate four years later -- renomination in 2006, instead choosing businessman and liberal activist Ned Lamont in opposition to the senator moving closer to the ideological center.

Will McCain's past fraternization with Democrats be enough to defeat him, especially in a year where anti-incumbency sentiments may be at an all-time high? It's too early to tell. With this new poll suggesting that support is building for J.D. Hayworth to challenge McCain, however, we may soon have the opportunity of finding out.

Jim Ellis is a former political advisor to the House Republican majority and currently provides election analysis for clients of the PRIsm Information Network. With Bennet Kelley he has formed Filibanter, to provide live presentations and media interviews combining political filibustering and banter.