The Turnbull government is said to have had its best fortnight yet but its three cited achievements: a superannuation compromise, some modest savings measures and showcasing Australia's border protection policies at the UN were all capitulations to someone else.

On super, Turnbull and Treasurer Scott Morrison surrendered to party conservatives who insisted that the backdated cap on non-concessional contributions was electoral rat poison in Coalition seats. On savings, the government accepted Labor's proposals rather than fight for its own. And on border protection, the Prime Minister, through gritted teeth, finally embraced the Abbott policies that he'd never liked.

For as long as the Turnbull government lasts, this is what we'll see: deals with Labor or the Greens to raise taxes, cut concessions or reduce so-called middle-class welfare; incessant discussion with the crossbench to produce watered down versions of the Abbott government's policies to get tough with militant unions; and look-both-ways, hedge-your-bets responses to any new circumstance that the government might face.

It's the Turnbull style: cut a deal, don't lead. In fact, he can't lead a centre-right party, at any rate because all his instincts are centre-left. Apart from being Prime Minister, the only things he actually believes in – same-sex marriage, a price on carbon, and an Australian republic – can't be pushed from the conservative side of politics. That, and the fear of bad polls, is why the Turnbull government is doomed to be a do-little one.

This week's Newspoll had Turnbull substantially more unpopular than the unpopular Bill Shorten and behind 48 to 52 on the two party-preferred vote. My hunch is that, in the future, the polls will oscillate between a draw and a Coalition loss. Turnbull's real problem won't be the polls, although people will delight in using them to score points against him, but his inability to craft a good reason to vote Liberal.

What is the point of the current government? If it's just to have Turnbull in the Lodge, rather than Shorten, voters are likely to conclude that they'd rather have a real Labor man than one who thought he'd get further by joining the Libs instead. That's why the same-sex marriage plebiscite is so fraught for Turnbull. He never liked it and only agreed to it as the price of rolling Abbott and getting a Coalition agreement from the National Party. If the Labor/Green/Xenophon bloc makes it impossible, Turnbull may eventually settle for a parliamentary free vote. But any departure from the plebiscite will strike large sections of the Coalition party room as a breach of faith.

Foreign Minister Julie Bishop is still resentful over Turnbull's vacillation on the Kevin Rudd UN appointment. Morrison is still angry over the prime ministerial veto of serious tax reform. House leader Christopher Pyne is smarting over the prime ministerial rebuke for losing control of the Parliament. It's not yet a toxic combination because all three are jealous of each other and eager not to let a rival get an edge. But it's not a recipe for stability.

Turnbull is still neurotic about Abbott, prompting one colleague to warn him that the real enemy is Shorten. Abbott, meanwhile, was laughing off prospects of return; insisting on the need to get real on budget repair; reiterating that Muslim migrants had to want to join Team Australia like everyone else; and suggesting that he could stop the sharks like he stopped the boats by implementing policies that had been proven to work!

Because he's not a Howard or Abbott-style conservative, Turnbull will always get some benefit of the doubt from the media. His colleagues won't want to emulate Labor a second time by changing leader twice. But they're also conscious of how vulnerable the government is to a union-funded marginal seats campaign. Last time, to win, Labor needed to target two dozen seats. Next federal election half a dozen will do.

You read it here first: by the middle of next year the destabilisation of Turnbull will start and will be orchestrated by someone who not only desperately wants to be PM but who already has form as a leaker.

Now who could that be?

Ross Fitzgerald is an emeritus professor of history and politics at Griffith University.