We're nearly 18 months away from the next Congressional election. But that's not too early for political ads and polls in Minnesota's Sixth District, where Republican incumbent Michele Bachmann faces another challenge from Democrat Jim Graves.

The first poll in anticipation of their rematch show the candidates running about evenly. The Star Tribune reports the survey by Public Policy Polling found Graves with a two percent lead, which is within the four percent margin of error.

The Star Tribune noted her 44 percent approval rating in a heavily Republican district could be an ominous sign for Bachmann. But since the poll was taken by a Democratic agency hired by Graves, the Bachmann camp gives it no credence. A Bachmann spokesman tells MinnPost Graves "can buy all the polls from Democrat firms he wants."

Bachmann's win in November came by just 1.2 percentage points, making it the narrowest of her four Congressional victories. Bachmann has already purchased ad time on Twin Cities TV stations, a move The Hill calls rare for a House race that's more than a year off.

Campaign finance investigations stemming from Bachmann's bid for the 2012 presidential nomination now involve the FBI, as well as panels at the federal and Iowa state levels.