WASHINGTON - In Florida, Virginia and Indiana, voters have received phone calls that wrongly told them there was no need to cast a ballot in person on Election Day because they could vote by phone.
In Ohio and Wisconsin, billboards in mostly low-income and minority neighborhoods showed prisoners behind bars and warned of criminal penalties for voter fraud - an effort that voting rights groups say was designed to intimidate minority voters.
And across the nation, some employers - notably David and Charles Koch, the billionaire brothers who help fund the conservative group Americans for Prosperity - are pushing their workers to vote for Republican Mitt Romney for president.
Two weeks before what could be one of the closest presidential elections in US history, efforts to mislead, intimidate or pressure voters are an increasingly prominent part of the political landscape. Analysts say tactics typically seen in the last few days before an election are already in play.
"We've seen an uptick in deceptive and intimidating tactics designed to prevent eligible Americans from voting," said Eric Marshall of the Lawyers' Committee for Civil Rights Under Law, who manages a coalition that has a telephone hot line (1-866-OUR-VOTE) that collects tips on alleged voter intimidation.
Democrats have been more vocal in complaining about such antics. They also cite groups linked to the conservative Tea Party movement that are training tens of thousands of people to monitor polling places on Nov. 6 for voter fraud. The controversial plan has been criticised as an attempt to delay or discourage voting.
But Republicans also have been behind some of the complaints, which have been focused largely on the eight or so politically divided swing states that are likely to decide the race between Romney and Democratic President Barack Obama.
Kurtis Killian, a Republican from St. Augustine, Florida, was among those in three states who have reported receiving calls that encouraged them to vote by phone so they would not have to go to the polls.
Killian said he received a call from a man who identified himself as an employee of the Florida Division of Elections.
Killian said he refused the caller's offer to cast his vote by phone then reported the call to local elections officials.
"I know there is no such thing as phone voting," Killian said. But "for someone who can't get out easily," such as elderly or disabled voters, "they might go for that - it would be convenient for them. Once you think you voted ... you won't go to the polls. My vote would be cancelled out."
Virginia's State Board of Elections received similar complaints from at least 10 people - most of them elderly - who said they had been urged to vote by phone.
Voters in Tippecanoe County, Indiana, reported similar phone calls in September, sparking an investigation by the Secretary of State's office, which oversees Indiana elections.
The probe has focused on a firm called Vote USA. It is unclear who was behind the group; its phone number is no longer active. The Secretary of State urged voters who receive a call from Vote USA to ignore it.