Police attended Jim Murphy’s visit to Fife because of an attack on the Scottish Labour leader before the independence referendum.
Two officers sat in a marked car outside FiFab Precision Steel Fabrications in Glenrothes as Mr Murphy visited the offices.
Independence supporter Stuart MacKenzie was sentenced to 80 hours of community service after throwing eggs at the politician on Kirkcaldy High Street just weeks before the referendum.
A police spokeswoman confirmed the decision to deploy resources was taken purely as “reassurance” after the previous attack.
A source added: “It makes sense to have the officers there just in case.”
It came as Mr Murphy insisted his party could retain all three of its seats in Fife, despite a new poll showing the SNP has almost doubled its lead over the party in the general election race in Scotland.
More than half of adults in Scotland who are certain to vote on May 7 (52%) said they would vote SNP, against 24% backing Labour, the TNS poll found.
The 28-point lead is nearly double last month’s figure, when the parties scored 46% and 30%, respectively.
The Conservatives scored 13%, down one percentage point, the Liberal Democrats 6%, up three points, and the Greens 3%, down one point.
SNP campaign director Angus Robertson said: “This poll is another very welcome indication that more and more people across Scotland are putting their trust in the SNP, and our message of delivering jobs and growth in place of Westminster cuts has huge appeal.”
Mr Murphy said he was “confident we can win” in Fife and claimed Labour’s canvassers are reporting more positive returns for his party than the national surveys report.
He added: “I’m confident we’ll do really well in Fife. I know the polls are really bad but the feedback on the doorstep is really good.”
“But we know we’re in a fight.
“We know that the SNP are neck and neck in some of these seats, but Kenny (Selbie, Kirkcaldy and Cowdenbeath), Mel (Ward, Glenrothes), Thomas (Docherty, Dunfermline and West Fife) and all of the others, I’m proud of them as candidates and they’re working every minute of the day.”