Despite a record number of registered voters this year, intense interest in the presidential election and the historic outcome, Ohio's voter turnout was lower Tuesday than in 2004, unofficial statistics show.

Secretary of State Jennifer Brunner is reporting 67 percent turnout, compared with 72 percent in 2004. She had been predicting 80 percent turnout this time.

The percentage could increase as provisional ballots, overseas ballots and other outstanding votes are included during the official canvass in the coming weeks.

But overall turnout still is expected to be lower than in 2004, leaving experts at a loss to explain it -- especially because the number of registered voters increased by 319,000 from four years ago.

"That's rather puzzling, given the activity level," said Paul Beck, a political-science professor at Ohio State University.

The total number of votes cast Tuesday declined in 69 of Ohio's 88 counties when compared with official totals from 2004. In Franklin County, for example, about 10,000 fewer votes were cast this year.

Although Brunner's office said the totals include 181,000 provisional ballots reported so far statewide, some counties said that's not the case. But the turnout percentage still will be lower than 2004.

Beck and others say one possible reason is a lack of enthusiasm among some Republicans for Sen. John McCain this year compared with President Bush in 2004.

McCain received more than 317,000 fewer votes than Bush statewide, based on early unofficial totals.

But Sen. Barack Obama also garnered nearly 22,000 fewer votes statewide than Sen. John Kerry did in Ohio four years ago, despite a massive get-out-the-vote effort.

Another interesting result is that the counties with the largest increase in turnout from four years ago -- Butler, Delaware and Warren -- are solid Republican or GOP-leaning counties.

And the counties with the largest declines -- Cuyahoga, Montgomery and Stark -- are more Democratic areas.

Obama garnered more total votes than Kerry did in those three Republican counties. And even though his margin of victory in many Democratic counties was larger than Kerry's, the president-elect's total vote still was lower in those counties.

John Green, director of the Ray C. Bliss School of Applied Politics at the University of Akron, speculated that one factor at play might be that both Republican and Democratic voters stayed home this year.

Just as some Republicans might not have been enamored with McCain and didn't want to vote for Obama, some Democrats might not have liked Obama and wouldn't vote for him, he said.

"Beneath all of this enthusiasm that we saw on Election Day, there may have been some discouragement," Green said.

Some observers also speculated there was nothing equivalent this year to the gay-marriage amendment in 2004 to help drive voter turnout beyond what the presidential race did.

But no one was willing to offer a definitive explanation without more analysis.

"I'm perplexed," said Herb Asher, professor emeritus of political science at Ohio State University.

mniquette@dispatch.com