For weeks he has been ploughing a lonely furrow addressing people from soapboxes in high streets up and down the country to warn of the dangers of independence.
Today, Labour's Jim Murphy joined an illustrious list of politicians who have been pelted with eggs.
However, the good humoured East Renfrewshire MP saw the yoke - or rather joke - while campaigning ahead of next month's poll.
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The incident happened while Mr Murphy was speaking to members of the public in Kirkcaldy, Fife.
The MP for East Renfrewshire was addressing locals as part of his 100 Towns In 100 Days tour of Scotland for Better Together.
He tweeted later: "Now off to another £indyref debate in Glasgow. Might look scruffier than usual but the egg stains aren't mine £WishI'dBroughtASpareShirt."
Police Scotland said they were investigating the incident outside the Mercat Centre at around 3.30pm.
Yesterday a speech by former prime minister Gordon Brown in Dundee was interrupted by a protester shouting "You're an absolute disgrace" before he was removed.
Earlier today, shadow foreign secretary Douglas Alexander was verbally abused by a caller to BBC Radio Scotland's Morning Call programme.
A Yes Scotland spokesman said: "There is no place for attacks - be they abuse, graffiti, vandalism or physical assault - in this campaign and we have been at pains to impress on everyone, on both sides of the debate, to treat others with respect at all times."
However, Mr Murphys in good company. Prime Minister David Cameron, Labour leader Ed Miliband and Deputy Prime Minister Nick Clegg, Ukip leader Nigel Farage and former Deputy Prime Minister John Prescott have all been hit with eggs in recent years.