The presidential election will likely be decided in 14 states.

The number 270 will come to dominate almost every waking moment for the Obama re-election high command in Chicago—as well as for their counterparts in the headquarters of the GOP nominee next year.

Two hundred seventy is the number of Electoral College votes needed to win the White House. Strategists on both sides will obsess on how to cobble together enough states to reach that total.

Since the 2008 election, 18 states have experienced a change in their number of electoral votes because of the decennial census. Some (mostly red ones) have gained electoral votes and some (mostly blue) have lost electoral votes. John McCain would have closed the gap by 14 electoral votes in 2008 if the contest had been run under the 2012 Electoral College distribution.

Most states are not in play. Mr. Obama will not win Utah and Wyoming, and the Republican nominee will not carry the District of Columbia or Rhode Island. But right now 14 states (with 172 electoral votes) are up for grabs.

Mr. Obama narrowly won three traditionally Republican states in 2008: Indiana, Virginia and North Carolina. Democrats last carried the first two in 1964 and the third in 1976.

The president will be hard-pressed to win these states and their 39 electoral votes next year, especially Indiana and North Carolina. Democrats will have their convention in Charlotte in an attempt to hold the latter. But a 2009 study by political scientists Michael J. Berry and Kenneth Bickers (of the University of Colorado at Boulder and Denver, respectively) found “no evidence that hosting a national nominating convention has any discernible effect on the ultimate vote in that state.”

Ohio, with 18 electoral votes, and Florida, with 29, both went Democratic in 2008 (they went Republican in 2004), but the swing in each was less than the national average. This indicates some weakness for Mr. Obama that has persisted: A recent Quinnipiac University poll in Florida shows the president losing to a generic, unnamed Republican by three points.

There are nine other states that have frequently been battlegrounds in recent contests. There is every reason to believe they will be so again.

According to recent polls (conducted by Public Policy Polling and the polling arms of Suffolk and Quinnipiac universities, the University of New Hampshire, and Dartmouth College), Mr. Obama trails former Massachusetts Gov. Mitt Romney in New Hampshire (four electoral votes), and he leads a generic, unnamed Republican by only one point in Pennsylvania (20 votes), a state he carried last time by over 10%. He leads a Republican (both unnamed and named) in the Midwest states of Michigan (16 electoral votes), Wisconsin (10), Iowa (six), and Minnesota (10)—but with less than 50%.

Then there are Western battlegrounds: Colorado (nine electoral votes), New Mexico (five) and Nevada (six). Mr. Obama leads in the first two with more than 50%—albeit in polls by Public Policy Polling, a Democratic firm that tends to be more generous to its party’s candidates. But in Nevada, Mr. Obama trails Mr. Romney in a poll conducted by the same firm.

The 2012 presidential election is likely to be decided in 14 states. If Mr. Obama loses the three states he narrowly carried in 2008 plus Ohio and Florida, then the GOP would win back the White House by swiping any one of the nine remaining battlegrounds. This is a good place for the party to be right now.

The GOP could benefit from the enthusiasm and new registrations generated in its primaries, just as Democrats did in 2008. It also helps that there are Republican governors in 10 of the 14 battleground states. Republican National Committee Chairman Reince Priebus is planning a big ground game in these states to register, persuade and turn out the vote.

Team Obama can’t afford to only play defense. They say they will make plays for Georgia, Arizona and Texas. The first is a long shot; the last two are either attempts to sucker the GOP into a defensive crouch or simply represent bravado. Neither state is likely to go Democratic.

The president’s team is already focused on its Electoral College math project. According to CBS Radio’s Mark Knoller, since January President Obama has made 40 stops in 15 states. Twelve stops were in battleground states and of the remaining 28 events, 15 were fund raisers in Democratic treasure houses like New York City, Los Angeles and San Francisco.

At this point, the 2012 election is shaping up to be much closer than 2008. Mr. Obama has the considerable benefits of incumbency but also a dismal record. The electoral map has shrunk for him: Key states that went for him last time are unlikely to do so again. This election is within the GOP’s grasp. The quality of the Republican candidate’s campaign and message will decide whether it becomes so.

This article originally appeared on WSJ.com on Wednesday, May 4,