Both the SNP and Labour have said they are concerned about the impact of voter ID in tomorrow’s Rutherglen and Hamilton West by-election.

The South Lanarkshire poll will be the first time voters anywhere in Scotland will need to show a form of photographic identification before casting their ballot.

The measure was brought in by the UK Government in a bid to tackle, personation is the electoral crime of pretending to be someone else to use their vote.

That's despite just 13 cases of alleged personation fraud recorded by police.

Recent analysis by the Electoral Commission found that at least 14,000 people were turned away from polling places and did not come back during May’s local elections in England, the first to require voter ID outside of Northern Ireland.

Hundreds of thousands of others, roughly 3% of all those who did not vote, said they did not even try to do so because they did not have appropriate identification.

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Speaking to journalists during a campaign stop in Blantyre, the SNP’s Katy Loudon was asked if she had worries about the impact of voter ID.

“I think it is a concern because we saw that it had a real effect on the local elections down south,” the candidate said.

“The worry is of course that if people are turned away from a polling station, are they going to come back?

“So we’re doing our part every time we’re speaking to people on the doorstep, we’re sending that message.

“Every leaflet that’s gone out, every election communication, Facebook adverts, every way we can think of to make sure that message gets across because make no bones about this, this move by the Tories in Westminster is about voter suppression.

“It was, and that’s just completely unacceptable.

“So it’s on all of us, and that is something I’m pleased to say, among candidates, we all seem to have agreed on as well, and we’ve all been working very hard to get that message out. I know that the council has, and the joint evaluation board who are in charge of the electoral roll in the constituency have been.”

The Herald: Humza Yousaf and Katy Loudon

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In Cambuslang, Scottish Labour leader Anas Sarwar said he hoped the new rule would not “undermine democracy”.

He said his activists were “reminding people constantly in all of our materials on the final week, all the doors we chap is to please make sure you take your id with you.

“Ultimately, we won't know until after the by-election the extent of the challenge that is forced upon people.

“We can only run the election within the rules that are given to us and imposed by it. And I hope it doesn't undermine democracy.

“I'm hopeful that people still get out and use their vote regardless of which political party they're voting for because fundamentally I'm a democrat.”

Today marks the final day of campaigning in what has been one of the UK’s longest by-election battles.

Both Labour and the SNP are expected to flood the constituency with activists for one last bout of doorknocking and leaflet delivering.

It is thought the result will be known by around 1am on Friday.