Bush, meanwhile, spent the day barnstorming across Florida, promoting his Social Security investment plan, saying that Gore was using "scare tactics" as he criticized Bush's tax cut plan.

With the race so tight, both parties have spent millions in extensive get-out-the-vote efforts that might be the deciding factor in some key swing states.

"It looks as if there are enough states where it's close enough so it's going to be a turnout election," said Kennedy School Lecturer in Public Policy Marty Linsky, adding that local races, ballot questions and the weather will all make a difference.

But despite the closest presidential race since 1960, most experts do not expect a high voter turnout tomorrow.

A lower turnout will favor Bush, according to Bradlee Professor of Government and the Press Thomas E. Patterson, because a disproportionate number of people who do not vote are low-income members of the Democratic base.

"The smaller and smaller the turnout gets, the more and more it works to the advantage of Republicans," Patterson said.

The campaign took a few unexpected turns on Thursday, when a Maine reporter broke the story that Bush had been arrested for driving under the influence in that state in 1976, and when Bush said that Democrats wanted to run Social Security "like it is some kind of federal program."