J. Kenneth Blackwell, Ohio's secretary of state, likes to tell a story about the elderly woman who approached him at a church function the other day:

"She said, 'I'm saying two prayers for you,' " recalled Blackwell, with a deep, rolling laugh. " 'The first is that you do the right thing. The other is, for your sake, I'm praying that this election is a blowout.' "

The anecdote says much about the scrutiny that has turned Blackwell's way in the closing days of the 2004 election -- and about his critical role in it. As the official charged with setting the ground rules about how Ohioans will vote Tuesday, Blackwell, 56, has become the most important official in a state that may determine the next president.

Blackwell's calls on election matters great and small -- from how heavy the paper stock has to be on a voter-registration form to whether independent candidate Ralph Nader should be allowed on the ballot -- have placed him in the eye of the storm, and at times have made him the storm itself.

Everyone, it seems, suspects that Blackwell has favored the other side. Democrats have accused Blackwell, a conservative Republican who co-chairs President Bush's statewide campaign, of trying to suppress the registration of poor and minority voters, a bloc likely to support Democrat John F. Kerry. Republicans believe that Blackwell, the highest-ranking African American ever elected in Ohio, was helping Democrats when he ruled last month that Nader had not collected enough legal signatures to qualify for a spot on the Ohio ballot. Nader asked the U.S. Supreme Court on Friday to review that decision; the high court turned down his request on Tuesday.

As he has been for weeks, Blackwell was in the spotlight Tuesday. With Republicans challenging the eligibility of tens of thousands of new voters, Blackwell issued new guidelines to county officials that make it easier for such challenges to succeed (if local election board officials are deadlocked about whether a voter is eligible, the voter loses). Democrats immediately went to federal court to stop the GOP challenges.

For his part, Blackwell says he has made the right calls -- and he points to a string of favorable court decisions to back him up. He also calmly rebuts suggestions of an impending Florida-style Election Day mess.

"Elections are a human endeavor, and my human instincts say there's no such thing as a flawless election," he said. "A lot of this is just partisan noise. The reality is, the system may be tested, but it will be okay."

That is the erudite, refined Blackwell talking, the man who likes to quote Jonathan Swift and Gandhi and was a university vice president, bank director and human rights ambassador to the United Nations before winning two terms as secretary of state. But a more combative Blackwell, who grew up poor in a rough Cincinnati neighborhood, has been on display over the past month, too.

When U.S. District Judge James G. Carr last week ruled against Blackwell's order that people holding provisional ballots must cast them in the precinct in which they reside, Blackwell called Carr "a liberal judge . . . who wants to be co-secretary of state."

For an extra measure of drama, Blackwell added that he would rather go to jail than rewrite his guidelines -- an idle gesture, as it turned out, after an appeals court overturned the judge's ruling.

Edward B. Foley, an expert in election law at Ohio State's Moritz School of Law, calls Blackwell's rulings "a mixed record" but does not see a pattern of political bias. "He's made some incorrect decisions, but also some defensible ones," Foley said. "Yet even on those he came up short on, I wouldn't attribute political motives."

A former Xavier University football star who still looks like one at 6 feet 5 and 250 pounds, Blackwell has made no secret of his ambitions -- he intends to run for governor in 2006. Blackwell, who opposes same-sex marriage and advocates a flat tax (he was national chairman of Steve Forbes's presidential campaign in 2000), said he considered a run for governor in 1998 but "buried his ambition" at the time. "Fortunately," he added, "I know where I buried it."

Foley, the law professor, called Blackwell "the third of three candidates" for governor, behind former attorney general Betty Montgomery and her successor, Jim Petro. Both are Republicans.

On the other hand, Foley said, this election could be a career-maker for Blackwell. "I wouldn't be surprised," Foley said, "if the secretary of state has an eye on his career when figuring out what decisions to make."

Ohio Secretary of State J. Kenneth Blackwell is setting the state's ground rules for Election Day.

He said both parties accuse him of favoritism.