In what is probably the most surprising poll of this cycle so far, a joint effort by the Democratic-oriented Rossman Group and the Republican-oriented Team TelCom for the Detroit Free Press finds that 27-term Democrat John Dingell of Michigan trails his Republican opponent Rob Steele by four points, 43.8 percent to 39.5 percent.

A Dingell has represented Michigan in Congress since 1932, when John Dingell, Sr., defeated Republican Charles Bowles in the newly-created 15th District, centered in Dearborn.  Michigan was still solidly Republican, so even in that Democratic landslide year, the margin was close.

Dingell, Sr., had close calls in the good Republican years of 1938 and 1946, but by the time his son took over the seat in 1955, the district had moved far enough toward the Democrats that Republicans could not come close even in great Republican years.  The only time Dingell ever fell below 60 percent in his lengthy career was 1994, when he received 59 percent of the vote.

In other words, this is a very surprising polling result.  If Dingell is truly down in this D+13 district, what does this say for Democratic chances in the 5th (D+12) and the 12th (D+13), neither of which appear to be on anyone's radar screens?