This Tueday President Barack Obama will face his first electoral test since assuming office. The president is not on the ballot, but in large measure his standing in American will determine the results of the New Jersey and Virginia governors’ races.

The two states are the only ones in the nation to elect governors in off-election years and as such, with nothing else to cover more or less, the national media pays a lot of attention to both races and both party leaders ascertain the national mood from the results of the races. In 1993, the Republicans won both governors’ mansions and next year in the mid-terms went on to capture the Senate and the House. In 2005, the Democrats won (or rather held-on) to both states and next year recaptured both houses of Congress. This year, Republicans are eager for a victory in order to rally the party after two major electoral defeats in a row. A Republican double-victory will also energize (and Republicans will claim foretell) the party for victory in the 2010 mid-terms. Conversely, a bad night for Democrats will worry the White House and party elders that the Democrats are losing appeal and may lose seats in 2010 (the Democrats’ majority in both houses are so strong that even if Republicans win on Tuesday and win next year, the Democrats will still retain a majority albeit one less robust). Obama will be seen as losing political capital and conservative Democrats, fearing next year elections, will be less likely to back many of the president’s domestic policies (something Obama can ill afford).

That is why the White House is working to avoid defeat. . . in New Jersey. Obama won Virginia (the first Democrat since 1964), but his popularity has fallen in the state and the Democratic candidate is behind his Republican opponent by more than five points. The White House has conceded that Virginia will be a lose (a reversal of trends in a state that Democrats have come to almost dominate), and in a leaked report to the media is laying the blame on the poor Democratic candidate to shield Obama from criticism that his relative unpopularity in the state is at fault for burdening the Democrat (an unfair charge, indeed, since Democrat Deeds is a loosy candidate).

But New Jersey offers hope for Democratic incumbent Corzine, a former Goldman Sachs CEO. Behind in the polls the entire summer, the emergence of an independent conservative candidate has spilt the Republican vote and put Corzine ahead. Obama has spent Sunday campaigning for Corzine (nothing for Deeds) in order to ensure victory in the state.

If the Democrats can win at least one state, they can prevent the Republicans from claiming some national mood change disfavoring the Democrats. The Democrats can then dismiss the Virginia lose as simply “win some, lose some” and nothing more. In 1993 and 2005, the respective parties won both seats and with such an plenary victory could energize the base.

Both half-wins do not do much in politics.