AUSTIN — Some voters have said their straight-ticket ballots have switched to candidates in the opposite party, but the company that makes the machines said they don't do that and have been used in the last nine election cycles without any problems.

Several voters have complained to Texas election officials that their votes for Rep. Beto O'Rourke switched to Sen. Ted Cruz, or vice versa, on Hart InterCivic's eSlate machine.

Houston resident Mickey Blake told KTRK-TV (Channel 13) that she voted straight-ticket Democrat, but on the final review screen, she noticed all Democratic candidates were selected except for O'Rourke. Cordell Hosea of Fort Bend County told the station that the same thing happened to him.

But Hart, which is based in Austin, blamed the problems on user error.

"County election officials conduct public logic and accuracy testing to ensure the voting system is programmed correctly and that it is capturing and tabulating votes accurately," the company said in an email. "The eSlate simply records the voter's inputs; it does not, and cannot, 'flip' or 'switch' votes."

Hart said its machines allow voters to view their ballot on a summary page before casting so they can verify they made the intended choices. The company said voters should seek help from elections workers if they have any problems or questions.

Dallas County doesn't use Hart's eSlate machines, but according to the secretary of state, they're in 82 counties, including Tarrant, which has 1,289. Travis County has more than 20,000, and Harris more than 8,100.

Keith Ingram, the state director of elections, published a notice Tuesday to address the problems voters were having after casting straight-ticket ballots.

"We have heard from a number of people voting on Hart eSlate machines that when they voted straight ticket, it appeared to them that the machine had changed one or more of their selections to a candidate from a different party," Ingram wrote.

He said the problem can happen when a voter pushes the keyboard before the page has fully loaded. Voters should be careful to push only one button at a time and not push "enter" until the page is complete, he said.

"As a reminder, voters should always carefully check their review screen before casting their ballots," he wrote in the notice. "If a voter has any problems, they should notify a poll worker immediately so the issues can be addressed and reported."

On Friday, secretary of state spokesman Sam Taylor told an ABC News station in Odessa that the office has trained election officials across the state and is required to keep a detailed log of malfunctioning machines and remove them.

"We will continue to educate Texas voters using existing resources," Taylor said, "and urge all Texans casting a ballot to take their time, slow down, and carefully review their ballot before casting one."

Sen. Ted Cruz's campaign emailed a statement Friday about the reported errors, advising voters that once they select the Republican party ticket, "please be patient and do not select 'next' until the ballot has populated all of the selections."

The Texas Democratic Party also sent a statement Friday, saying the secretary of state's office knew about voting machine malfunctions and did nothing about it.

"The malfunction can lead to straight-ticket Democratic voters casting a ballot for Republican Sen. Ted Cruz if they don't review and correct their ballot before pressing the red cast button," the party wrote.