Vote Flipping: Donald Trump says its being used to rig the election, but what is it?

Mr Trump appears to be seizing on genuine problems to increase worries that the election won't be fair

Poll workers look on as US President Barack Obama (C) gestures towards the press as he votes early at the Cook County Office Building in Chicago, Illinois, October 7, 2016 (JIM WATSON/AFP/Getty Images)

Donald Trump claims that voting machines are rigged so that they force people to choose the wrong candidate. He’s only half wrong.

The Republican candidate is encouraging the idea that “vote flipping” is prevalent in voting machines being used in the US election. That phrase refers to a strange behaviour sometimes seen in the machines – that they appear to pick a candidate that the voter didn’t actually choose.

It mostly happens when people press on the electronic touchscreen that’s used for voting. When they press, another candidate appears to be highlighted.

The problem has worried the people it has happened to, because it appears to indicate that the machines could be biased towards a particular candidate. And that worry is extra prevalent this year, when a range of commentators are claiming that the election is going to be rigged against Mr Trump.

Reports of vote flipping are already pouring in from the states that use voting machines for early voting. They have been reported in North Carolina, Texas and Nevada.

The problems led the North Carolina chapter of civil rights group the National Association for the Advancement of Colored People to write to the state’s board of elections to voice their concern about the problems.

The issue does appear to be real, and prevalent. But it’s not so much an indication of vote rigging as a consequence of old and slightly rubbish voting machines.

Voting experts have pointed out that actually allowing people to see that their vote had changed would be a terrible way of rigging an election. In almost all cases, voters can change their wrongly entered vote after it’s entered, and if not they can inform voting officials who will let it be corrected.

Instead the problem seems to be that the old voting machines just aren’t especially good at sensing where on their screens they’ve been pressed. The hardware is wearing out and the screens are badly calibrated, meaning that they sometimes think that someone is pressing somewhere they aren’t.

And over the day, the screens get a thicker and thicker layer of grease and other things from people’s hands. That can make them even more wrong, and make people’s selections look even stranger.

Mr Trump encouraged the worry by tweeting out a message about the prevalence of vote flipping. It gained traction quickly, being retweeted thousands of times within minutes.

The lines that Mr Trump refers to appears to be the fact that the problems with vote flipping are leading machines to be taken out of service. As a result, people are able to vote less quickly – and so queues are forming outside polling places.

Experts have warned that people shouldn’t worry about apparently vote flipping, and just make sure that if there are any problems then officials are made aware.