"Parties are using social media to [effectively] deliver leaflets," he told an audience at Advertising Week in London today (24 March) in a session called The Election, The Economy, The Consumer: The Future of Europe.
The YouGov chief executive suggested social media activity is for the most part preaching to the converted, and those people talking up its power as a political campaigning tool are businesses with a vested interest in doing so.
Shakespeare said: "All pollsters are guessing that the Conservatives might win, but it’s not based on data, it’s more a hunch.
"The fact is that Miliband is not profoundly [liked or respected], especially among the swing voters. People have more difficulty imagining Ed Miliband as prime minister and that’s key.
While shifts in the polls are forecast to become more dramatic as 7 May draws nearer, Shakespeare said at present, YouGov polls are showing a 1%-2% lead for Labour.
"In normal circumstances, a 2% majority translates to those votes – a Labour majority of two seats."
But, he underlined the decline of support for the main parties, with Labour and the Conservatives getting a smaller vote share. "This means we get an increase in how small differences can affect the outcome," he said.
"We could end up with the party with the most seats and votes not being the party running the country, because of the shrinkage of the main parties.
"We think that the Conservatives are just about the biggest party, but it’s a long way off a majority. Labour and the Lib Dems together could only just squeeze a majority."
But YouGov expects the polls to shift as the election nears, with three main factors influencing voter sentiment: values, competence and who the electorate feel would make the best prime minister.
In terms of values, which 44% of voters consider the most important influencer, the Tories are "way behind" with Labour still "out of touch".
On competence, the Tories are "strongly ahead", viewed as being ahead on issues such as the economy and immigration, while Labour are viewer as competent on the NHS.
But voters consider Cameron as the best MP for prime minister, "way ahead of Miliband", while Osborne is viewed as the best chancellor over Ed Balls.
The offer of a referendum on the EU is attractive to voters, even if Shakespeare reckons the outcome will be a 'yes' vote, in spite of initial excitement over the prospect of independence.
"If Cameron wins, I think the debate over Europe will be over," he said. "It’s why the outcome of the election will have a very important historical effect."
Meanwhile, Shakespeare explained how YouGov used its consumer data gleaned from 450,000 UK panellists to gauge the preferences of voters who have become Ukip supporters, with the groups split between 'Blue Ukipers' and 'Red Ukipers'.
While both groups share a love for comedian Jim Davidson, the blues prefer figures such as Jeremy Clarkson, Boris Johnson and Margaret Thatcher, while the reds like Piers Morgan and Michael Barrymore.