WASHINGTON -- Only days before millions of Americans cast their ballots, a climate of suspicion hangs over Tuesday’s national elections.

Accusations of partisan dirty tricks and concerns about long voter lines, voting equipment failures and computer errors are rampant, particularly in key battleground states such as Ohio and Colorado, where absentee and provisional ballots could decide a close election.

“Those will be the states that are the most prone to confusion and chaos and contesting if the election is close or within what some people call the ‘margin of litigation,’ ” said Charles Stewart III, a political science professor at the Massachusetts Institute of Technology.

State and local election officials and partisan watchdogs are on high alert for problems, as is the U.S. Department of Justice. All of them plan to post election monitors at potential trouble spots across the country.

The extra preparations will certainly help, but they haven’t stopped reports of phony election workers showing up at people’s homes to collect their absentee ballots or anonymous callers falsely claiming that voters can stay home on Election Day and cast their ballots by phone.

With concerns running high about voter intimidation, voter suppression and poorly trained poll workers, many think that the integrity of the elections – and the officials who run them – has been compromised. Nowhere is that more true than in Ohio, where Republican Secretary of State Jon Husted has drawn the ire of Democrats by limiting the amount of time for early voting.

“It’s highly unfortunate that the rules of the game have become hyper-politicized,” Stewart said. “It sets up a situation that, regardless of who wins the election next Tuesday, the losers, especially the most zealous partisans, will be set up to doubt the legitimacy of the outcome.”

In their national bid to root out voter fraud, True the Vote, a conservative organization, might have hundreds of thousands of poll watchers nationwide. They plan to challenge voters they suspect of casting ballots illegally. This could slow the election process and force challenged voters to cast provisional ballots, which are counted later.

“True the Vote has reported instances of procedural and technical errors occurring in polls that could lend themselves to abuse,” a statement by group founder Catherine Engelbrecht said.

Labor organizations and voting rights groups, such as Common Cause and the Lawyers’ Committee for Civil Rights Under Law, also will have poll watchers making sure that voters aren’t harassed, intimidated or threatened by True the Vote members.

“Our monitors will be monitoring their monitors,” said Judith Browne Dianis, a co-director of the Advancement Project, a national nonpartisan voting-rights organization. “We are going to make sure they’re not engaging in bullying at the polling places.”

The recent high-water mark for voter distrust is the 2000 presidential election, when Florida’s disputed votes and the resulting challenge to the U.S. Supreme Court left the race undecided for several weeks. The high court eventually declared Republican George W. Bush the winner.

Concerns about the 2012 election mushroomed last year as Republican state lawmakers around the country introduced a series of restrictive voting laws that critics claimed would affect minorities, college students and the poor disproportionately. Democrats and civil rights advocates argued that the laws were a less-than-subtle attempt to suppress the votes of some of the party’s strongest supporters.