CLEVELAND - In many ways, the runup to Ohio's presidential primary today has been a prelude to the runup to the Nov. 4 general election.

For weeks, the candidates have been constantly criss-crossing the state, occasionally coming close to bumping into each other. Thousands of campaign ads and robo-calls have washed over Ohioans. The candidates' ground troops are everywhere.

"Ohio is in the eye of the storm and the eyes of America will be on you," Gov. Ted Strickland told a gymnasium full of Democrats over the weekend. "We'll do our part on March 4 and again on November 4."

It's unusual for Ohio to matter much in the presidential nominating race because its primary is relatively late in the election cycle. And, in fact, only the Democratic contest between Hillary Rodham Clinton and Barack Obama has been hard-fought, with John McCain's victory in today's Republican voting considered a foregone conclusion.

Historical swing state

Come November, though, it will be a whole different ballgame. Election after election, Ohio has been the nation's premier battleground state.

"In the entire history of the Republican Party, no Republican has ever been elected without winning Ohio," former President Bill Clinton told supporters of his wife on Saturday, noting appreciatively that he had taken the state twice.

Strickland, Hillary Clinton's most high-powered supporter in the state, went further, calling Ohio "the most critical swing state in November. ... I represent 11.4 million Ohioans who represent a microcosm of America."

The most recent edition of the Almanac of American Politics noted Clinton's historical observation about the state, adding, "no Democrat, in today's electoral vote arithmetic, can be sure of winning without it."

The seventh-biggest state in the nation, Ohio has 20 electoral votes, which have long been seen as crucial to winning the White House. It is something of a bellwether, with its presidential vote totals consistently mirroring the nationwide totals.

It happened again in 2004, when President Bush matched his national average in Ohio and John Kerry won 1 percentage point more than his average. And Ohio was the state that put Bush over the top and back in the White House for another four years; had Kerry won another 120,000 votes in the state, he would have been elected.

State has a blue-red divide

Of all the big Midwestern industrial states, Ohio has been the most consistently Republican, but a series of upset Democratic victories in the 2006 midterm election may continue to reverberate this fall.

Those results have strengthened the Democrats' bench strength, and a strong field of officials and party operatives have intensified the ground games waged by both Hillary Clinton and Obama.

Despite its longstanding Republican reputation, Ohio is unevenly divided geographically, another quality that places it up for grabs every four years.

An arc of counties along the northeastern and eastern boundaries of the state are deeply Democratic blue, their biggest prizes the cities of Cleveland, Akron and Youngstown. Almost the entire remainder of the state is a vivid Republican red.

As for Texas, where today's other big primary is being held, it will likely be largely ignored by the eventual nominees this fall even as Ohio is avidly courted. It has become so completely Republican that no Democrat has been elected to a statewide office in the past 14 years.

Bob von Sternberg • 612-673-7184