I'm a former Liberal chief minister and senator. Here's why the Coalition should call it a day

Let's face it: it's always been a marriage of convenience, a vehicle for grabbing the benefits which come from holding government rather than a true meeting of minds. In recent years the federal Coalition has more resembled a marriage where the partners stay together for the sake of the children or the tax advantages, but where the love has long since dried up.

At the heart of the problem is the fact that the National Party is a party of vested interests, whereas the Liberal Party cannot afford to be. The metamorphosis in the 1970s/1980s from the Country Party to the National Party was intended to free the party from its image as an agrarian power bloc, but the transformation never followed the name change.

Except to some extent in the Queensland Parliament, it never made the transition to representing urban Australians. It is still the Country Party in all but name.

While the Liberal Party has a historic association with the business sector, it is far less wedded to that sector than is, say, the Labor Party to the trade union movement. Of the three major parties in the House of Representatives, the Liberal Party is the one least the hostage to an obvious vested interest, the one best able to claim to advocate for the nation as a whole - at least in theory.

Being handcuffed to the party of agrarianism does nothing for the Liberal Party's capacity to speak to a broader Australia. On issues such as net zero by 2050, the need to compromise with the narrower preoccupations of the Nationals has damaged the Liberals, both in perception and in reality.

Ironically, the long-standing, almost mechanistic alliance with the Nationals seems to have hindered the Liberal Party's capacity to form alliances with others. It is the Labor Party, not the Liberal Party, which has been better at forging cross-party deals in recent years, despite the latter's long experience of coalitions.

Good examples were the failures of the Kennett government in Victoria in 1999 and the Abbott federal opposition in 2010 to clinch support from rural independents who held the balance of power. In both cases the ALP stepped up to deals that secured them government, deals that mysteriously eluded the conservative side of politics.

Walking in lockstep with the Nationals also fails to accommodate the changes in political culture washing over Australia and almost all the democratic world.

READ: Coalition back together for second time in eight months to defeat 'awful' government

Support for long-serving "major" parties has been falling the world over. Here, the Australian Election Study (AES) has mapped falling loyalty for the major parties. In 1967 some 80 per cent of Australians voted for the big three; by 2025 that figure had fallen to 55 per cent, and shows every sign of continuing to decline.

What this means is that, notwithstanding Labor's present thumping majority in the House of Representatives, majority governments in the future will be more and more elusive. Parties will be more likely to need to negotiate supply agreements for minority governments or even coalitions with unlikely bedfellows.

This approach has long been the practice in continental Europe, where governments are generally formed by multi-party coalitions, and partners are not necessarily those parties closest to each other on the political spectrum.

Alliances between green parties and parties of the right have not only occurred, but have sometimes demonstrated surprising durability. This aligns with the almost universal voter sentiment in the Western world rejecting "politics as usual" and seeking compromise, negotiation and power sharing.

The Liberal Party will need to be adaptable and nimble in this new environment. It may be, for example, necessary for it to accommodate the agenda of the teals if a Liberal government is to be formed. Dragging the National Party into the negotiating room is unlikely to assist that process.

This is not to say that cooperation with the Nationals has to end. What may better suit both parties are casual hook-ups rather than a steady relationship.

The Liberal Party presently suffers from policy deficit. Voters are simply unsure what it stands for. Having given away its lead over Labor as the party best able to manage the economy - again, evidence from the AES - it urgently needs a root-and-branch revision of its policy platform, one that will address in particular the alienation from the party of younger voters, women and migrants.

With the National Party currently obsessed with chasing One Nation off to the right, the Liberal Party can ill afford the drag its former coalition partner will exercise over this process of policy renewal. Liberal policy should be Liberal policy, not an anaemic compromise with the narrower vested interests of the Nationals.

No one can say that they haven't tried to make it work. The trial separation less than a year ago was a real chance to work through their differences, but very soon after the Nationals moved back into the marital home it was clear that the differences were irreconcilable. For the Liberals, attempting to maintain a facade of romance that once was leaves them at risk of ultimately walking away penniless from a messy divorce.

Change the locks, move on.