The Republican National Committee on Thursday called upon Secretary of State Scott Gessler and elections officials elsewhere to look into reports of malfunctioning touch-screen voting machines that may be casting votes for Barack Obama when a voter meant to pick Mitt Romney.

In Colorado, Republican officials pointed to a single example of a malfunctioning machine in Mesa County.

“I understand that, in a significant number of cases, voting machines in your states have populated a vote for Barack Obama when a voter cast his or her ballot for Mitt Romney,” John Phillipe, the Republican National Committee’s chief counsel, wrote in a letter to Gessler and the secretaries of state in Nevada, Ohio, Kansas, North Carolina and Missouri.

“I further understand that the causes of this problem are varied, and include miscalibration and hyper-sensitivity of the machines,” Phillipe wrote.

The GOP asked that voting machines be recalibrated before the polls open Tuesday, that extra technicians be provided and that polling places remind voters to double-check before submitting their selections.

In Arapahoe County, where touch-screen machines are the principal means of in-person voting, Clerk Nancy Doty, a Republican, said the request to recalibrate the machines on Election Day was unreasonable.

“We have 650 machines,” Doty said. “They’ve already been tested.”

In Mesa County, which uses the machines for early voting and to assist disabled voters, County Clerk Sheila Reiner, a Republican, said a machine at an early-voting center was discovered to be malfunctioning when a man tried to use it Monday. When the man touched the screen, it recorded his selections in the wrong place.

Reiner said there had been only three votes on the machine before the man used it and that none of those voters complained about it. Still, the machine was taken out of service, she said.

Rich Coolidge, a spokesman for Gessler, a Republican, said the office was still reviewing the matter.

Staff writers Sadie Gurman, Carlos Illescas and Ryan Parker contributed to this report.