Casual political observers might have been baffled by the high-profile way that top aides to President Barack Obama have tried to pressure Democratic Gov. David Paterson out of New York’s 2010 gubernatorial race.

Since polls show the state’s first black governor probably can’t win a primary, let alone a general election, for the job he inherited from scandal-tarred Elliot Spitzer, the Obama folks seemed to be stirring unnecessary trouble at so early a date.

Two parochial factors — and one broader concern — explain it.

Many New York Democrats fear Paterson could cost several U.S. House seats, the state Senate and control of legislative and congressional redistricting, as well as the governorship. They’re also concerned that failure to resolve the matter might tempt former New York Mayor Rudy Giuliani, a potentially strong Republican candidate, into the race.

In a larger sense, though, the New York maneuvering — and strong White House interest — underscores the importance of what could be the most significant elections over the next 13 months: for nearly 40 governorships and most legislatures, including in Texas.

While the 2010 congressional elections will determine the Congress for the second part of Obama’s term, these state elections will shape the make-up of the U.S. House and many legislatures for the next decade.

So while Republicans will face an uphill battle to win back the House and Senate next year, a strong GOP showing in state races could help them to regain control of the House later in the decade.

That’s because those results will determine how congressional and legislative seats are reallocated as a result of the population shifts in the 2010 census. In turn, they could enable the party that controls a state’s political machinery to strengthen itself, as Texas Republicans did after the 2000 census.

The Lone Star State remains a good example of how this works, largely because it could gain as many as four U.S. House seats from population growth.

While much of that increase is in heavily Hispanic areas, which mostly vote Democratic, continued GOP legislative control could enable Republicans to protect, or even bolster, their current 20-12 majority.

And even if the Democrats managed to win one legislative house, they’d have a hard time denting the GOP hold on the five-member Legislative Redistricting Board, the five top officials who can reapportion if the legislature fails to act.

Other states that partisan shifts could affect next year are Florida, which may gain two seats, and several large Northeast and Midwest states, which will lose House seats because of population changes.

After the 2000 census, for example, Republican control of normally competitive Pennsylvania, Michigan and Ohio enabled the GOP to draw district lines that gave it a 33-19 majority in those states’ congressional delegations.

But the Democrats have gained majorities in all three states in the past two elections and have expanded their 20-9 margin in New York to 26-3.

Along with a 20-seat margin in California, Democrats need to maintain those majorities to offset the GOP’s advantages in Texas, Florida and other Sun Belt states. If they don’t, and Republicans currently seem to have a good chance of winning the governorships of Ohio and Pennsylvania, the GOP could regain through redistricting what it recently lost at the polls.

The 2010 battle for state control actually starts next month with elections for governor and legislature in generally Democratic New Jersey and emerging battleground Virginia, where Republicans have held the legislature while losing the past two gubernatorial elections.

The results could affect congressional seats in both states.

In Virginia, despite Republican legislative control, Democrats now have a 6-5 congressional margin; in New Jersey, slated to lose a seat after the census, they have an 8-5 advantage.

For much of the latter half of the 20th century, Democratic control of states helped them maintain their majorities in the U.S. House.

But after each of the last two censuses, strong Republican state showings helped them in the subsequent redistricting. That underscores the importance of those 2010 elections — and why the Obama White House is so interested in them.