From the New York Times:

The Nov. 3 contest in upstate New York’s 23d Congressional District, an 11-county area where registered Republicans outnumber Democrats by 45,000, is shaping up as a test of a struggling GOP and a possible gauge of Obama’s coattails.
Obama, who carried the district by 5 percentage points in his landslide victory in New York last year, forced the special election when he named the incumbent, Republican John McHugh, his Army secretary.
The president will host a fund-raiser for the Democratic candidate, Bill Owens, tomorrow in New York City. The seat is one of three that the Republicans control in the state’s 29-member congressional delegation.
In a fund-raising e-mail for Owens, Clinton called the special election “bigger than just one candidate or one office . . . victory or defeat will also be seen as a referendum on President Obama’s agenda.’’