didn't work was 2004, when they lost but the incumbent still won the Presidential election.
Since 1940 when the Redskins moved to D.C. the teams outcome in its final game before the presidential election has predicted which party would win the White House each time but once.
When the Redskins win their game before the election, the incumbent party wins the presidential vote. If the Redskins lose, the non-incumbent wins.
The only exception was in 2004, when Washington fell to Green Bay, but George W. Bush still went on to win the election over John Kerry.