From The Fix:

New York Rep. John McHugh is President Barack Obama's choice to be the new Secretary of the Army, a decision likely to set off an extremely competitive special election for the Republican's 23rd district House seat.

A senior White House official confirmed that Obama had chosen McHugh for the post, news that was first reported by the New York Times' Carl Hulse this morning.

McHugh has served in Congress since 1992 and has served on the House Armed Services Committee since 1993; he is currently the ranking minority member on the committee.

The 23rd covers the farthest reaches of upstate New York, from Plattsburgh in the Northeast to Oswego on Lake Ontario.  The Northeastern counties along the Canadian border have a strong Democratic tilt to them, while the remainder of the district is more Republican.  The district went narrowly for Barack Obama over John McCain and for George W. Bush over John Kerry.  It is fairly characterized as a swing district.

The special election to replace McHugh will be a tea-leaf-reading festival for pundits.  The district is slightly more Democratic than the neighboring 20th district, which Republicans lost in 2006 and failed to take back in early 2009.  If Republicans were able to hold the 23rd, they would attempt to propogate a meme that Republicans are primed to come back in the Northeast.  A loss would be taken as further proof that Republicans are doomed to at least semi-permanent minority status.  Republicans occupy most of the state-level offices, so they should be able to run a competitive candidate, but that did not help them in the 23rd.

It is also noteworthy that this is the second northeastern Republican from a competitive district that the Obama Administration has enticed into leaving his seat -- the first being Senator Judd Gregg.  There's nothing new here; the Bush Administration famously tried, without success, to convince Ben Nelson to join his Administration (which would have given Republicans 56 Senators beginning in 2005), and reportedly came close to snagging John Breaux as Energy Secretary in 2001 (the seat went to David Vitter after Breaux retired).  What's new is Obama's success.

In the long run, this won't matter much.  As the Fix notes, New York is slated to lost a Congressional seat in 2010 and is on the cusp of losing a second.  McHugh's district is a prime candidate for pruning, and whoever wins could be in for a short Congressional career (especially if it is a Republican).  But in the short run, the continuation of the theme that Republicans are on their heels is priceless for the Obama Administration.