Like Gordon Brown, George Osborne is a deliberate drawer of dividing lines.  He carves them out both between the Conservatives and their enemies – the welfare trap; the surplus trap, and so on – and within the Party itself, separating those who please him from those who cross him.

If you are a Friend of George and scratch his back, he’ll scratch yours: Sajid Javid, Nicky Morgan, Amber Rudd, Greg Clark, Greg Hands, Matthew Hancock, Robert Halfon – all sit around the Cabinet table, and are either open members of Team Osborne or have served under him at the Treasury.  In case new Tory MPs were in danger of missing the point, the Chancellor made it himself at a recent meeting of the Treasury Support Team.

But if you are a critic or a outright opponent, your name and number will be taken. Having a run-in with Osborne is not necessarily a bar to promotion: two MPs who reportedly had rows with him, Tracey Crouch and Andrea Leadsom, are Ministers today (indeed, the latter was for a while in the Treasury team itself).  The Chancellor is cool-headed enough not to bear grudges, or at least be seen to do so.  But crossing Octopus Osborne is a hazardous business for the career-minded: his tentacles are everywhere.

Right from the start, he has been Chief Executive to the Prime Minister’s Company Chairman – in opposition and government.  This is the same arrangement as existed between Tony Blair and Gordon Brown, but it is an infinitely more harmonious one, based on friendship rather than a deal.  The steadiness of the Cameron-Osborne relationship is the rock on which opposition, coalition and now majority government have been built.

Indeed, the Chancellor might almost be said to be co-Prime Minister, and certainly wants to succeed Cameron when he leaves Downing Street – perhaps as soon as next autumn, in the wake of an early EU referendum.  This ambition leaves a question trailing in its wake.  Could this divisive figure unite the Conservative Party – especially in the wake of a poll that will divide it, starkly and visibly?  Can this warrior also be a healer?

The question is all the more pressing because of the conditions brought about by Cameron’s pledge to leave Number Ten before the 2020 election.  The Prime Minister’s gaze is focused on the renegotiation and referendum.  This is not simply because of its significance to the country.  It also holds the key to interpreting his record.  A referendum victory would mark Cameron’s third plebiscite win.  He would also retire undefeated in two elections.  He will already be mulling how he will be remembered.

In short, the Prime Minister can gaze into the sunset into which he will duly ride off, and afford not to worry too much about what will happen afterwards.  Some believe there is evidence that he is doing so already – claiming the absence of a strong central grip on the selection for the London Mayoralty candidate, in which Downing Street is likely to be landed with a winner, Zac Goldsmith, who if victorious next May will surely campaign for No and is certain to oppose Heathrow expansion.

Osborne does not have this luxury.  He wants to be in place as Party leader and Prime Minister for 2020.  Some sources claim that he is already more sensitive to Party management than Cameron – for example over the handling of the recent vote on purdah.  This week, all eyes will be on his first budget as Chancellor in a majority Tory Government.  And today’s papers are duly packed with leaks: a paring-back of green subsidies, cuts to the BBC, no more cheap rents for better-off council tenants.

We will write about the Budget itself in more detail tomorrow.  But it is worth taking a moment, at this start of a big week for Osborne, to ask that big question.  Differences within parties on constitutional issues can sometimes be kept under wraps, at least for a while.  Referendums, however, flush them out into the open.  Politicians have to choose one way or the other.  Language loosens.  Loyalties are strained. Tempers rise – as members of one party campaign with others against their colleagues.

Osborne will hold a major share of the responsibility for handling the resources of government, the management of the party machinery, and relations with senior colleagues who hold a different view from his.

Can he somehow keep Inners and Outers from moving apart in the run-up to the referendum, and bring them together afterwards to campaign for a common victory in 2020?  Can this man-who-would-be-leader demonstrate to the Party that he believes “we’re all in this together”?