While the two campaigns Tuesday accused one another of trying to steal or suppress votes, experts in election administration are focusing on the old standbys: Faulty machines, questionable voter lists, last-minute litigation.
The likely trouble spots, the experts say, include two familiar election reprobates: Ohio and Florida.
But there are also some new entrants, as the broad new playing field of the 2008 presidential election means more states are competitive, more citizens are participating, and the potential for Election-Day meltdowns like the notorious administrative collapse in Florida in 2000 has increased.
Many pointed, in particular, to Colorado as the possible source of a late night November 4, while others suggested that record turnout in states like Virginia and Georgia could challenge local election officials.
"There's still reason to be concerned in terms of what's going to take place in November," said Kimball Brace, whose firm, Election Data Services, advises local governments on election administration.
Brace cited everything from new machines in Cleveland and South Florida to the rise in absentee voting, many of which are counted by error-prone "optical scan" machines.
"The states that we're keeping an eye on [are] still Florida, but also Ohio, and also Colorado. Those three states are the problem ones from an election administration standpoint," he said.
The location of an Florida-2000-style Election-Day meltdown - with the attendant legal clashes, and lingering doubt - is impossible to predict. Such crises only come about in extremely tight elections, and require the confluence of that close vote with an administrative failure.
But despite eight years of federal and state efforts to create a more standardized, higher-tech national framework for election administration, most state votes will still be administered by county election boards whose competence and equipment vary wildly.
The campaigns, meanwhile, have already begun intense legal skirmishing in states like Ohio and Indiana over a new wave of early voting that began in September.
"In South Florida you've got areas that are going to be on their third separate voting technology in their third consecutive presidential election," said Doug Chapin, the editor of the non-partisan Electionline.org. "Ohio once again is in ground zero for policy changes and litigation."
Colorado, meanwhile, is still reeling from a true Election Day meltdown in 2006, a technical failure in Denver that may have swung at least one close race.
"It's squarely in both campaigns' sights," Chapin said. "They were one of the last states to finish their voter registration list. They had a very bad experience with Election Day voter centers in 2006. Lots of changes, lots."
Many states are taking pressure off their November 4 poll sites with a push for early voting, which has been embraced by both presidential campaigns.
"Mail-in voting helps to relieve a lot of the pressure," said Rich Coolidge, a spokesman for the Colorado secretary of state.
But Chapin said early voting comes with its own concerns: The error rate for optical-scan ballots transported to a central location for counting is sharply higher than those tallied on site, he said.
Florida, the state that has been synonymous with Election Day chaos since the 2000 recount, remains especially troubled despite intense local efforts to remedy its problems. A 2006 congressional election was marred by a dispute concerning more than 18,000 "undervotes" on ballots that registered votes for some offices but not for the congressional race itself. The losing campaign claimed that unusually high number of undervotes was due to a software glitch on "touch-screen" voting machines.
In preparation for the presidential election, 15 Florida counties complied with a new edict to abandon their touch-screen voting machines, and switched to optical scan machines, which leave a physical record of each voter's ballot in case of a recount. But this August in Palm Beach County, a close local primary where 3,400 ballots went uncounted - followed by a series of recounts - led officials to worry and re-test the optical scan voting machines.
"We feel pretty good about the machines," said Jennifer Krell Davis, the communications director for the Florida secretary of state, who said most had had a test-run in this year's presidential primaries.
But just in case, "All of the supervisors have been encouraged to plan as if there is definitely going to be a county-wide recount," she said.
Some observers say that the main problem may simply be delays, and depressed turnout, as voters navigate the new machines.