There are an average of 15 such families for every marginal voter.

Typical marginal voters are therefore the least likely to vote Yes.

Each party, then, must attract many marginal voters.

When marginal voters were reminded that their seat could decide the election, the Tory lead rose from six to eight points.

Fortunately, the referendum "undecideds" are not traditional marginal voters.

In the UK, such marginal voters are predominantly social and economic conservatives who identify with institutions like the monarchy.

Moreover, being political beasts, they inevitably succumb to the lure of the marginal voter and the pork barrel.

Politics here remains focused on the marginal voter and, post-Keating, has eschewed communicating a framework of ideas that might provide coherence to policy.

Contemporary electioneering is based on "triangulation": getting close to the opposition parties in policy, in order to nibble their marginal voters.

Worse, George Galloway endorsed Miliband for prime minister - just the sort of thing to scare off marginal voters.

Hard conservatives and the religious right now say the Republicans can rebuild by intensifying the policies and rhetoric that drove those marginal voters to Mr. Clinton.

Voting results with or without logrolling will differ only if the minority is more interested in an issue than the majority, enough to separate the marginal voters from the majority.

You’re going to win these marginal voters in part by finding issue positions that solve practical problems they face - hence the reason candidates take so many positions these days.

Labour minders searching for crumbs of comfort after the weekend's election debacle might be forgiven for trying to blame the fickle marginal voters of south-east England.

To the atmosphere generated by the yearning faithful, add the element of competing with or complementing showbizz, and a leader performs, where the marginal voter wants to be talked to.

It is hard to really actuate long-term change when you have to concern yourself almost exclusively with that very small percentage of marginal voters in marginal seats in western Sydney.

"Last time around, the Republican candidate didn't get that marginal voter that's going to elect a Republican in the state, the pro-lifers and the Second Amendment voters," he said.

"It is especially critical at the end of the campaign when you are looking for the marginal voter," said Jonah Seiger, managing partner at Connections Media, an Internet strategy firm.

"It essentially exists because of the poor image and reputation of big banks and, in particular, the poor image of big-bank mergers with marginal voters in marginal electorates."

But she cited 1984 in noting that Republicans do better in legislative races in a Presidential year, in part because a strong Presidential contender brings marginal voters to the polls.

Obama’s advisers obviously have calculated that making a big deal out of free medical care for the working poor, and perhaps winning the support of marginal voters like Tichenor, would lose far too many middle class votes.

"However, if we don't deal with the situation," Mr. Coltart said, "if we don't establish what the facts are and discipline where necessary, there will be marginal voters who may question our ability to govern."

What swayed marginal voters towards the Tories was not David Cameron’s supposed charisma, but something much more concrete: a cast-iron promise of very large tax cuts to a small but clearly targeted and identifiable group.

While Mr Cameron enjoyed a 13-point lead over Gordon Brown as the person who would make the best prime minister, marginal voters did not feel he understood their problems any more than his Labour rival (37 per cent each).