New York's 20th District, which includes all or parts of 10 counties in the Hudson Valley, is one of those districts that proves party registration is not always an electoral indicator. In recent years it's disproved election history, as well, leaving political prognosticators and practitioners unsure of tomorrow's special election outcome.

The race to replace Sen. Kirsten Gillibrand's (D) former House seat has been called a referendum on President Obama's economic policies, as well as a preview of the 2010 midterm elections. Both parties have poured resources into the race, though the DNC may be trying to hedge its bets, while the NRCC and RNC are going all-in.

Inside the campaign, Jim Tedisco's (R) years of public service (and voting records) have been the target of Scott Murphy's (D) campaign, while Tedisco has attempted to tie the political novice's career as a venture capitalist to Wall Street's role in the dismal economy.

In the district, Republicans lead Democrats in voter registration by a wide margin -- some 67,500 as of November 2008. And, according to the Almanac of American Politics, this area has been Republican territory since the birth of the party. George W. Bush won here by 7 and 8 points in 2000 and 2004.

However, these stats did little to help Republican Sandy Treadwell, whom Gillibrand defeated by 24 points in November. Nor did then-incumbent John Sweeney, who lost to Gillibrand by 6 points in 2006, gain from the sizeable party-ID edge or GOP record in the district. Obama also won the district by 3 points.

In New York's unique ballot system in which candidates can be placed on mulitple lines, both Sweeney and Treadwell won placement on three party lines: Conservative, Independence and Republican -- giving them an even larger registration advantage. Gillibrand was endorsed by the other two parties: Democrats and Working Families. This time, the Dem candidate will get a third line, as Murphy has been endorsed by the Democrats, Working Families and Independence parties.

The race will come to a close tomorrow night, and the victorious party will surely claim a bigger victory than a sole congressional district. Murphy's poll numbers appear to put him on track for a victory, so we'll also see tomorrow night if polling is any better indicator in NY-20 than party ID or history.

(Cross-posted on RCP's Politics Nation)