Texas voters experiencing issues with voting machines used in that state have been told by election officials that they are the problem, not the machines. The state says voters are inadvertently touching the machines in ways they shouldn't, causing the machines to alter or delete their vote in the hotly contested senate race between Republican incumbent Ted Cruz and Democratic challenger Beto O’Rourke.

The issue in the senate race has occurred when voters chose the option to vote a straight-party ticket—that is, to vote for only candidates from a specified party. Depending on whether the voter indicates they want to vote Democrat or Republican, the machine will automatically populate all races with candidates in the chosen party. But the multiple-page ballot can take several seconds to complete—in Houston the ballot runs 16 pages long. The Secretary of State and county election officials have blamed the issue on voters touching the machines while the systems are still rendering the ballot on screen—thereby inadvertently de-selecting their vote in the critical senate race. They say voters who touch the "enter" button while the system is still filling out the ballot can cause the machine to de-select their chosen candidate or change the vote to the other candidate in the race. Only between 15 and 20 voters—both registered Republicans and Democrats—have reported problems so far to the secretary of state's office, though more may have experienced it without noticing, if they failed to review their ballots before casting them.

The problem involves eSlate voting machines made by Hart InterCivic—direct-recording electronic (DRE) machines that use a dial and button for voters to make their selections. Voters turn the dial in the lower right corner of the machine to scroll through each race and page of a digital ballot, and press the "enter" button, located just left of the dial, to make their selections.

But Dan Wallach, a computer science professor at Rice University in Houston who has examined the systems extensively in the past, told Motherboard in a phone interview that the problem is a common type of software bug that the maker of the equipment could have fixed a decade ago and didn’t, despite previous voter complaints. What's more, he says the same systems have much more serious security problems that the manufacturer has failed to fix that make them susceptible to hacking.

The issue is occurring primarily with the US Senate race because that's the first race at the top of the ballot, Sam Taylor, a spokesman for the secretary of state told the Texas Tribune. The first screen voters see on the machines asks if they want to vote a straight-party ballot, and if they indicate they do, the next screen that appears is the first page of the multi-page ballot, already filled in by the machine with votes for candidates in the party they chose.

Leah McElrath, a freelance writer who specializes in political analysis, is one voter who experienced the problem in Houston. She waited 45 minutes in line to cast her ballot, she told Motherboard in a phone interview, and when she got to the machine, she selected the option to vote a straight-party Democratic ticket. She's positive the first page of the ballot then showed a vote cast for O'Rourke because when she saw the machine highlight his name, she says she did "a happy dance" in her head. But when she got to the review screen at the end of the ballot, she saw that the machine had given her vote to Cruz instead. McElrath says she did manually change some of her selections on the ballot to Republican candidates after the machine filled out her straight-party choices—something the machine allows voters to do—but insists she didn't do this in the senate race.

"They have literally … made zero changes on these machines," Wallach said. "The software we are running today here in Houston is exactly the software that [we] looked at in 2007."

She was able to easily change the vote back to O'Rourke before casting her ballot, but she was so concerned about the switch that before she did this, she took a picture of the review screen with her phone, showing the vote for Cruz. She didn't report the problem to election workers at the time. "I didn't want to be alarmist," she told Motherboard, and she assumed it was a one-time anomaly, until she started hearing news reports that other voters had the same problem.