I do think that parties lose elections rather than win them. " I've had enough of this lot..lets give someone else a chance." add to that what seems to be a growing trend to abstain from voting.
there is also maybe a feeling that the electorate is not catered for. Party 1 has this plat du jour. Party 2 has that plat du jour. if you don't like fish, or chicken , you've had it.
I agree with you on that. If there were a general election tomorrow, I doubt I'd bother voting. This would be the first time I'd not voted in my life. Even since living in a Tory enclave where my non-Tory vote is barely noticed against the blue tide I've gone out of my way to vote.
I accept that parties will never fully match what I want. When I switched from Labour to the Lib Dems I did it knowing that they were wildly out of line with my views in many ways but there were other like minded people as me in the party and my views were accepted. Now, the Lib Dems have "professionalised" in that they're far less tolerant of loudly dissenting internal voices; someone like me who thinks that nuclear power is the only viable long-term guaranteed power source used to be tolerated, now they're hushed up to ensure that there's an undiluted party line. The sole time I was REALLY comfortable with my views being aligned were with Labour under John Smith in the 1990s.
As far as I'm concerned, the current Labour party aren't far away from the Tories of the 80s in terms of political views. The Tories are not sure what they want to be, half of their policies try to drag them to the centre, the other half drag them towards swivel eyed lunacies. The Lib Dems are a soulless bunch of opportunists, they'd happily switch to supporting Labour tomorrow if it got them a wee bit more time in power while being nothing more than a "me too!" squeak tolerated by the Labour leadership. UKIP are just against things, they have no policies of their own to deserve such a large opinion poll percentage. The Greens are the swivel eyed loonies of the left. The BNP are the pustulent boil on the backside of UK politics. Screaming Lord Sutch is dead.
On my original paragraph, the only way I'd vote if there were an election tomorrow would be to keep a UKIP or BNP candidate out.