It may seem odd even to contemplate anything beyond polling day but it is certainly not. Even party stalwarts accept that there will be a significant difference in votes between constituencies with sitting Liberal Democrat MPs plus, perhaps, a handful of other target seats, and the rest of the country. Twenty years of targeting has succeeded in diminishing the party's base in most of the country. The Rochester and Strood by-election last November was far more of a disaster than can be imagined or was acknowledged. There was a time when the party thrived on by-elections when at least it was possible to bring party workers into a constituency to build up the party's vote and, if nothing else, to build up the local association for future elections. However, Rochester and Strood was the worst by-election result ever for the Liberal Democrats or the Liberals. We lost 7,450 votes of the 7,800 we polled in 2010. My concern is that the combination of resurgent UKIP, SNP and Green parties, with too many constituencies neglected for decades, will produce many similar results on 7 May. That is why there needs to be a preparations for an immediate plan to rescue the party, constituency by constituency.

Targeting is a peculiarly Liberal Democrat self-caused wound but the causes of the rise of UKIP apply to all the established parties. The combination of massive disillusion with these parties and their long term failure to confront the perverse views of a substantial number of their supporters has been lethal. The seeds of the mainstream parties' vulnerability to the populist appeal of UKIP, (and to a lesser extent the principled appeal of the Green party and, for Labour in Scotland, the calculated positioning of the SNP), were sown long ago. At election after election the parties have been content to retain the votes of a significant number of voters whose personal beliefs were widely at variance with the values of the party. Any one who has canvassed white working class voters on any council estate is aware of the widespread anti-immigrant and reactionary views of many electors who declare themselves lifelong Labour voters. The Labour party was happy to have the electoral support of these voters believing that they had nowhere else to go. Similarly, in industrial West Scotland, Labour regarded the historic allegiance of the considerable working class vote as a permanent given. In our first-past-the-post electoral system, the party was not even worried by the declining electoral turnout in its traditional fiefs, after all the vote wasn't going anywhere else and it was still winning a wide swathe of these seats. Given all this, the leakage of votes, particularly to UKIP, was an electoral blow waiting to happen.

The former West Riding Director of Education, Sir Alec Clegg, highlighted the political cynicism of this attitude back in 1973: "Some of the industrial towns of the north are places that combine maximum need with minimum resources and overwhelming dereliction ..... There are whole areas of our country affected in this way and nearly all of them are in the industrial north. They lack both the charm of the countryside and the amenities and entertainments of the town. Further more they are areas of no political consequence. The 'left' know that they will not lose them and the 'right' know that they cannot win them, and so both political sides can ignore them, and exploit them politically, socially, economically and educationally without fear of reprisal."

The far right - the National Front or the BNP - never had much traction with these voters but a "respectable" far right party such as UKIP, made viable by a couple of Conservative MP defections, has exposed Labour's vulnerability to the seduction of many voters who realise that they actually agree with UKIP's populism. Similarly, in Scotland, the growing dissatisfaction with Labour's neglect and complacency has been cleverly seized upon by the SNP which is now providing a viable and non-Conservative alternative in many traditional Labour constituencies.

It is a curious irony that Labour's Blairite attempts to widen its appeal beyond its traditional class-based loyalties has made it more not less vulnerable to the defection of members of that class base to UKIP and the SNP. It is not a phenomenon unique to Britain: the plight of the Parti Socialiste in France has precisely the same problem with the abandonment of the party by many of those in the high rise suburbs surrounding Paris. Even before Marine le Pen deliberately made the far right Front National more "civilised", 40% of its support came directly from the Parti Communiste! Now the threat to the whole left is increasingly acute and only Jean-Luc Melenchon of the Left Front appears willing to take on the Front National on any kind of intellectual basis.

Historically it was the same situation in the USA where, until the Barry Goldwater election of 1964, the Democrats could always rely on the most right wing "bloc" vote in the states - the southern Democrats, who were programmed historically to oppose the Republicans because it was a Republican, Abraham Lincoln, who had promoted the civil war against the southern states in order to maintain the union. Eventually, this traditional loyalty to the name rather than the policies was eroded by the successful efforts of Ronald Reagan to seduce what became known as "Reagan Democrats."

The Conservatives have tended to make a virtue of not being ideological even though the party has over the long years amassed a corpus of philosophy. This has never prevented the party from opportunistically absorbing other political forces, such as the Liberal Unionists from 1886 and the National Liberals from 1931. If these precedents led the party to believe that it could assimilate UKIP it has clearly failed, not least because David Cameron cannot square the circle of appeasing UKIP sufficiently over Europe whilst maintaining the UK's crucial involvement with the EU. One of the few David Cameron comments I've agreed with was his description of UKIP as being made up of, "nutters, fruitcakes and closet racists."

The Liberal Democrats are the most vulnerable of the established parties to the seductions of the minor parties. They have a much smaller loyalist base and therefore need to put much more effort into promoting their political values and philosophy in order to avoid having to rely on the capricious and debilitating perpetual motion of local personalities and the ubiquitous "Focus" leaflets. Apart from a handful of places, such as Eastleigh, Southport and Sutton and Cheam, and a few others, where they have succeeded in persuading electors to have an allegiance to the party's basic political values, they have failed to embed these values. Too often canvassers meet the elector who expresses a rooted objection to the EU but who expresses enthusiasm for voting Liberal Democrat. One mumbles a non-commital response and moves on. Once there is another apparently viable party vying for the populist and for the "none of the above" vote the Liberal Democrats are in serious trouble. The lack of interest in, and attention to, persuading the electorate to support the party as such rather than relying on fake opinion polls, populist campaigns, continuous petitions and instant compassion, has left the party vulnerable to a party such as UKIP that peddles even more populist fantasies.

The difficult but healthy task of persuading the electorate to vote positively can be assisted by a change in the electoral system. The present lottery of first-past-the-post is itself damaging to the enhancement of politics and the development of a politics of values. A move to PR - single transferable vote - in multi-member constituencies encourages more attention on positive and co-operative ideas and policies rather than the negativism and recourse to tactical voting under FPTP. The evident problems for governance of the "lottery election" puts the case for electoral reform squarely back on to the agenda.

The obvious fact for all these established parties, and particularly the Liberal Democrats, is that they simply cannot ignore the threat to their effective survival. There is no longer a deference vote nor a significant class vote and they cannot rely on the complacency and naivety that has served them well over long years. It is going to be necessary to develop a politics of values whereby the parties set out their view of society and are prepared to argue for it. Unless they take on the oppositional attitude of UKIP and the expose the inherent dangers of the SNP's nationalism - and, indeed, point out the contradiction that a Green party is based on an analysis not on a prescription and that its success minimises the green imperative that needs to underpin the policies of all parties - their electoral future is bleak. For us, twenty years of targeting compounds the problem and we need to be planning now, even before polling day, to swing into action immediately after what is likely to be a generally depressing overall result on 7 May.