Alex Deane: The offer we should make to UKIP is clear. You endorse our candidates. We'll endorse your agenda.

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We shall soon begin selecting prospective Conservative Party candidates to fight seats at the next General Election. There is much discussion about whether we should seek a pact with UKIP. Here at ConHome, Paul Goodman says no, Andrew Lilico says yes. I agree with Andrew, but as my grounds are different - or different enough - I think it's worth airing here.

It is exceptionally likely that Conservatives with strongly Eurosceptic views will be selected to stand for us in many seats. Those wishing to stand are progressively generally more Eurosceptic (just look at the 2010 intake) and they're certainly, as a general rule, being selected by Eurosceptic Associations.

But given the ongoing rumblings about the settlement of our relationship with the EU, especially after the pledges made before the last election, we can guarantee that each and every candidate - and sitting MP - will be challenged by their local press, by UKIP, and by interested think tanks - are they in favour of a binding in/out referendum or not? If they are, will they campaign for the UK to come out?

Those who are not in favour of such a referendum may struggle to get selected – and if they are selected, they will face UKIP candidates at the polls. In some cases, the votes cast for these UKIP candidates will be the difference between the Conservative candidate winning and losing (making the challengeable but generally reasonable assumption that a large proportion of these votes would otherwise have been cast for us). We saw that at the last election in a clutch of winnable seats and there is no reason to believe that it won’t happen next time – indeed, as I set out below, it’s likely to be worse.

Those candidates who are in favour of such a referendum will either be in agreement of a Conservative Party platform with that policy, or they'll be in disagreement with it. If such a referendum is our policy, then why not do a deal with UKIP? Our platforms are the same! If it's not our policy, then the media witchhunt we've seen before will happen again. The leadership will be asked - again and again -  "will you disendorse/deselect/condemn/evict this candidate, who favours a referendum and therefore explicitly opposes your own policy?" If they buckle and let the sceptics stay, then it's bad: they've got the confusion and lack of clarity that a disjointed and compromised platform gets you, but with none of the benefits that a UKIP deal would bring. If they don't buckle, then it's worse: they're forced to deselect candidates (and sitting MPs?) for taking a stand against their own party line (one which is principled or ostentatious, depending on your view).

But whether it's because of the votes we'll lose, or the Eurosceptics amongst our Association volunteers we shed (via alignment with UKIP or simply staying at home, in either case), I think it's clear that we will be handicapping our candidates - and our prospects of forming government - if we don't make such a deal.

And now's the time to do it. Because if we leave it until after the next European Election in 2014 in order to "see what happens" at the polls then, it will be too late. For UKIP will most likely win it. They're polling in double digits pretty frequently, and (of course) do exceptionally well at European elections. They've gone from fourth to third to second in the last three polls - their trajectory is clear, and the public is more Eurosceptic and disillusioned with the main parties than ever. So their hand just gets stronger as time goes on. The terms available from them for such a deal will get worse, with them potentially being unwilling to do it at all in the end. And who could blame them, having waited for us to sharpen up our act for so long, if they did that?

Their demand is for a binding commitment for an in-out referendum on Europe - we should give it to them. Most of us want it anyway. The earlier we do it, the better. It gives more time for UKIP members and sympathisers to “come back” to us – either formally, or informally. And if not that, then at least they can “lend” us their votes, as many Tories lend ours to them at European elections – UKIP has an increasingly mature and stable set of supporters, but many of them will prefer to support Tories over Labour, especially when facing the question of whether they prefer the former or the latter to form government – but to display the genuineness of one’s position, and convince naturally sceptical people burnt by past experience that we’re “for real” with such a pledge, it will take time and a consistent message. We should get to it. It’s my firm view that the leadership must not push those of us who believe in this position out of our party – after all, there are many of us and it would schism the party very harmfully if that were to happen – but beyond that, I also think that strategically this deal is wise.

UKIP's demands are more palatable to us than the Liberal Democrats', because their worldview is closer. The Coalition has been a reasonable and mature compromise given the numbers produced at the last general election, but it is/was for a season rather than the longer term. Consider the principled policy differences between the parties which have bedevilled the Government since May 2010 - from tuition fees to the NHS to Europe to the welfare system and so on. These divisions are wholly reasonable: but there is simply no such gulf between us and UKIP and The longer we leave it, the odds are that we shall have less and less in common, as UKIP develops platforms across different policy areas and we continue to lose members from the right of our party to them: but for now, if we're honest the gap on most issues is pretty small. There are vast areas of commonality. If we can do a deal, we should. And with no offence meant to the social democrats amongst the Liberal Democrats (whom I imagine will actually take it as a compliment), it's self-evident that we've more in common with UKIP than with them.

The offer we should make to UKIP is clear. You endorse our candidates. We'll endorse your agenda.