The Colorado Secretary of State's Office is investigating after some Pueblo voters say voting machines switched their pick from Mitt Romney to Barack Obama.
The Pueblo County Republican Party said they've heard of more than a dozen reports of the problem.
One voter, who didn't want to use her name, told KRDO Newschannel 13 that when she hit the touchscreen for Romney, a check mark appeared next to Obama's name. She said she asked for help to fix the problem, but still feels unsure about her vote.
"I wonder where my vote really counted," she said.
Pueblo County Clerk and Recorder Gilbert Ortiz said he's aware of "fewer than ten instances "of the issue, but he said it's happened to both Republicans and Democrats in their attempt to vote for president. He said he blames human error.
"Just like when you're texting on your cell phone or using any other touchscreen technology, there's a chance that you might think your finger is touching one area and it's actually touching another," said Ortiz. "It might be dragging your knuckle, we've seen that error also."
He said the DRE (direct-recording electronic) machines have been used since 2006, and this type of error has happened before.
Gilbert points out that voters have several chances to change their ballot before casting it, and said everyone who's experienced a problem has gotten help and voted how they intended to.
Still, some are worried that there are voters who didn't notice the machine error, and this problem could persist on election day.
"How many more times has this occurred? None of us know," said Chuck Schneider, a poll watcher who said he learned of the problem from a Democratic election judge. "This could have a significant effect on the election in this county."
Pueblo Republican Chair Becky Mizel said this highlights the importance of voters double checking their print out ballot before casting their vote.
"At the very minimum, we would expect the county clerk's office to post a note on the door (of polling places) and have judges tell our voters there could be a problem with the DRE machine," said Mizel.
Both Mizel and Gilbert said they have been in touch with the Colorado Secretary of State's Office. Gilbert said representatives will be in Pueblo on Monday to test machines.
The machine voting error is also being investigated in Mesa and Arapahoe counties and in several other states. The Republican National Committee has contacted secretaries of state in Colorado, Nevada, Ohio, North Carolina, Kansas and Missouri asking for machines to be tested before election day.