Talk about damning with faint praise.  The good news for Barack Obama from an independent poll taken in Illinois is that he has a positive job-approval rating and that he leads other Republican contenders.  The bad news?  Well, let’s just say that there seems to be a lot of change in the Land of Lincoln (h/t William Amos):

President Barack Obama would win his home state of Illinois against any one of the top four Republican challengers for the office if elections were held today, according to a new poll from the Paul Simon Public Policy Institute at SIU Carbondale.

But the victory isn’t a landslide, as the results of the institute’s recent statewide poll show Obama’s job approval ratings are weak – and Gov. Pat Quinn’s are worse. …

Meanwhile, barely half of Illinoisans approve of the job Obama is doing in office, and they think even less of the performance of Gov. Quinn. The poll shows 51.8 percent of respondents think Obama is doing a good job, while 46.4 percent disapprove. Institute officials add, however, their results show a 10-point higher favorable rating for the president than the latest national Gallup Poll.

At St. Louis Today recalls, Obama won his home state by a wee bit more than 5.4 points in 2008; he carried Illinois 62/37.  He beats Republicans in head-to-head matchups in this poll as well, but note well that the gaps are much closer:

The new poll shows Romney still leading the GOP field comfortably over the nationally surging Herman Cain, which isn’t all that surprising. Illinois Republicans tend to be a moderate bunch and often go for the establishment types even when their fellow party members in other parts of the country are flocking to firebrands.

The bigger surprise is that, while Obama beats all Republican challengers in Illinois, Romney gets within 8 points of him. Obama has a more comfortable lead over Cain (46.3 to 34), but still fails to break 50 percent. Ditto with his 49.3-30.3 showing over GOP third-place finisher Ron Paul.

When an incumbent can’t get to 50% against challengers in the other party’s primary, that’s a big red flag in any state.  Undecideds usually break hard against the incumbent, and being below 50% means that the possibility of a loss becomes much greater, especially if turnout shifts in favor of the opponents.  When that occurs in an incumbent President’s home state — especially one so solidly Democratic as Illinois — it’s practically a cue for a dirge.  Pat Quinn’s 35% job approval rating as Governor isn’t exactly helpful either, as it will depress enthusiasm and grassroots efforts to turn out the vote.  Obama may have to avoid Quinn in order to campaign effectively, and that won’t be easy to do.

Does this mean Republicans could end up winning Illinois in a general election?  I wouldn’t bet money on that outcome, but that’s not the real issue here.  What this means is that Obama will have to bet money on Illinois, and a lot of it, to keep the GOP from taking his home state in November 2012.  That’s money that Obama won’t be spending elsewhere, like Virginia, Ohio, Florida, and North Carolina, and other states that he needs to keep in order to win re-election.