NICOLA Sturgeon is poised to lead the SNP to a historic third term in today's Holyrood election, as the virus of anti-Semitism poisoned the final hours of Labour's faltering campaign.

Ruth Davidson, the Scottish Conservative leader, spoke confidently of beating Labour into a humiliating third place as the racism row engulfing Jeremy Corbyn's leadership at Westminster spread north of the Border.

Labour suspended a councillor in Renfrewshire amid claims of anti-Semitism, and Kezia Dugdale, the Scots party leader, admitted the growing crisis was being raised on the doorsteps and was damaging her campaign.

Scots go to the polls today in the fifth Scottish Parliament election since devolution in 1999 with victory for the Nationalists assured.

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It will give the SNP an unprecedented third successive term in power and provide a personal mandate for Ms Sturgeon, who became first minister following the resignation of Alex Salmond in the wake of his independence referendum defeat.

In a combative polling day article circulated by the SNP, Ms Sturgeon said her opponents "cannot be trusted" to use the sweeping new powers over tax and welfare that will be handed to Holyrood during the lifetime of the next parliament.

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She also insisted Scotland was a better country than in 2007 when the SNP first took power.

"That, I firmly believe, is the result of having a government that always puts Scotland first. We are the only party prepared to stand up for Scotland at every turn," she wrote.

Her 800-word article makes no mention of her plan to push for a second independence referendum if support for leaving the UK increases, but it insists "education will be my number one priority".

Ms Sturgeon closed her campaign yesterday with a rally in Glasgow centre centre.

It was interrupted briefly by a protestor waving a Union flag, a moment that served to symbolise the ongoing constitutional debate which has dominated much of five week campaign.

Despite polls showing her party comfortably on course to achieve an outright majority at Holyrood, Ms Sturgeon urged people to give the SNP both their constituency and regional votes to "guarantee" it retained control of the parliament.

As the Nationalists cruised to a historic victory, Scottish Labour found itself embroiled in the anti-Semitism row that has engulfed the party at Westminster.

A senior councillor in Renfrewshire, Terry Kelly, was suspended by the party as it investigated comments he made about the "Jewish lobby" in an online blog.

Labour confirmed his suspension, along with that of another councillor south of the Border, as Mr Corbyn clashed angrily with David Cameron during Prime Minister's Questions over allegations of racism in both parties.

Ms Dugdale faced questions about the anti-Semitism row as she drew her campaign to close in one of the party's few target seats, Edinburgh South.

"It has unquestionably had an effect," she said.

"I am not going to go into the business of analysing what has happened over the past few days, but it is coming up on the doorsteps."

READ MORE: Scottish Labour leader Kezia Dugdale says she will reply to group over anti-semitism

The row destroyed her hopes of focusing the final day of the campaign on her plans to protect public services with a 1p increase in income tax.

One Labour insider said the party's battle with the Tories for second place was now "too close to call".

Internal polling last week showed a clear advantage for Labour, the source said, but they added: "With the week Labour UK-wide has had, it looks like that has ebbed away."

Ms Davidson, who also ended her campaign with a rally in Edinburgh, insisted her party was on course to inflict a catastrophic defeat on Labour and become Holyrood's main opposition party.

Asked what evidence she had, she said: "External polling, internal polling, on the doorstep and around the country - the whole shebang."

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Party strategists were slightly more cautious but were in no doubt the Scots Tories would enjoy their best ever night in a Holyrood election, bettering the 18 seats they won in 1999 and 2003.

Labour is on course for its worst ever result.

From a high of 56 seats in the first Holyrood poll in 1999, the party's tally has slipped at every subsequent election and is expected to dip from 37 five years ago to between 20 and 25.

Under the parliament's proportional voting system, The SNP is expected to claim around 70 seats, on a par with the 69 they took in 2011, if recent opinion polls are repeated today.

Despite a campaign that has largely failed to capture the public imagination, SNP strategists are hopeful of a high-turn out, which would increase the party's chances of a big majority.