I understand why Glenn Reynolds is suspicious, but I think this primary challenge of Charlie Rangel by former campaign director Vincent Morgan is legitimate. To begin with, the possibility was first reported about a month and a half ago, and that article notes an important detail about NY-15:
Someday, whether it be 2010 or 2012 or 3012, Charlie Rangel will not be the congressman from Harlem. There may not in fact be another African-American congressman from Manhattan, since a huge influx of white and Hispanic residents have moved into the borough in recent years.
Redistricting is set for the 2012 elections, and if Rangel is still around, political observers say, how his district’s lines move will give a clear message about the seat’s future. If the district moves northward into the Bronx, it will, first of all, no longer be the only district to be entirely in Manhattan, and, secondly, show that Rangel and his allies intend for the seat to remain African-American. If the district moves to the south, it would favor a white candidate and mean that black political power has effectively switched to the outer boroughs. If the district stays the same, then New York will likely send the first Dominican-American to Congress.