The problem is that by their very nature right-of-centre parties do not come to power with genuinely radical plans for change. Even the most revolutionary of British political movements of the past 50 years - the Thatcher government - did not come in in 1979 with grand plans for change and only started to implement large-scale reform after the 1983 election. In most eras and at most times, Conservative parties promise a break from the legislative and political turbulence offered by left-of-centre parties. It is therefore difficult for a right-wing party to attract the kind of head of steam that a left-wing party can, and instead the content of the campaign is likely to be generated by the party faithful, a group seperate and apart from the mass of the population which the party wishes to attract.
The result is that instead of "Change we can believe in" we get mush which is likely to make people more likely to favour the opposition, not less. Here's an example:
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The other posters aren't much better.