While he might just scrape home in the election on July 2 – and even that is problematic given the unfavourable opinion polls – a narrow victory will see his government returned, but at a considerable personal and political cost.

To justify his coup against Tony Abbott last year, what Malcolm Turnbull needed most was to win a significant mandate in his own right – that is, not only retain government but hold on to much of the Coalition's 30-seat majority. That now looks highly unlikely.

The eight months in office for Malcolm Turnbull have been anything but comfortable: he has been riding an electoral mandate won by Tony Abbott, heading a government that is still very much an Abbott government and, to all intents and purposes, has pursued a policy course almost indistinguishable from that of his predecessor.

Hostility towards the prime minister from within the government since the coup has been scarcely concealed, and to remove that hostility, Malcolm Turnbull needed to make the game his own, not one he stole. He is, and looks set to remain, a leader under threat and of dubious legitimacy to many of his own nominal supporters.

The idea of an Abbott comeback is simply fantastical: his prime ministership ranks as one of the great failures, along with Joseph Cook (1913-14), James Scullin (1929-32) and William McMahon (1971-72). But the fact that he will still be there, like Banquo's ghost, will haunt Malcolm Turnbull as long as he continues to be prime minister.

Almost certainly, the 30 or so Abbott supporters on the government side will be able to blithely ignore the looming disaster Tony Abbott was leading them towards and point instead at the squandered mandate from the 2013 election. The many failings of Abbott will be glossed over; the shortcomings of Turnbull will be magnified.

A narrow win for the government will tie the prime minister's hands in shaping the government more to his liking, both in terms of personnel and policy. Turnbull might win a three-year term, but will still be in Abbott's shadow – almost a lame duck prime minister. To reinvigorate his prime ministership, he needs a fresh team, bold new policies rather than talk and a story of his own. It is unlikely he will have that freedom of action.

A slender majority for a re-elected Turnbull government will have the Liberals concerned about the election after 2016, one that will see Labor within striking distance, and that, too, will spell danger for Malcolm Turnbull's leadership. Scott Morrison might well be encouraged to stake a claim for the top job (with no other potential candidate in sight). That will perpetuate the existing tensions and distract the government from governing, the last thing the country needs.

Since the departure of John Howard, the Liberal Party has floundered, despite having been in office for the past three years. Howard, like Fraser and Menzies before him, was the last of the Liberal strongmen, those dominating figures who could keep a team together, win elections and put a personal stamp on both party and government.

The loss of Howard at the 2007 election, and the departure of his heir apparent, Peter Costello, soon after left a vacuum that has never since been filled. Brendan Nelson and Malcolm Turnbull contested the leadership, with the party opting for Nelson as the one most likely to preserve the Howard legacy. That was a rear-view mirror decision, if ever there was one.

Turnbull eventually ousted Nelson, but met fierce resistance from within his own ranks, eventually falling to a revolt sparked by Tony Abbott's resignation from the front bench. Turnbull was challenged by both Joe Hockey and Abbott and in an extraordinary ballot, in which Hockey was eliminated first, Abbott and Turnbull went head to head with Abbott winning by a single vote – but with a handful of Liberals who had voted for the spill preferring to switch back to Turnbull if Abbott was the only alternative. It was hardly a vote of confidence.

Tony Abbott had the political luck for the Labor government to self-destruct; his win in 2013 was more a result of Labor's bastardry than his own political skills.

That Abbott was unable to make the party his own is now clearly seen. A strong Liberal prime minister can get his own way for his personal wishes even if his colleagues demur, but Tony Abbott's miscalculation over such issues as the knighthood for Prince Philip showed that he was never in complete control. John Howard was given his head on his pet bugbear of industrial relations (even though it was a key factor in the 2007 defeat), Malcolm Fraser had his freedom to deal with the white supremacist regimes in southern Africa despite colleagues' misgivings and Bob Menzies could do almost anything (although he was overruled in trying to call the decimal currency unit the Royal).

The failure of Malcolm Turnbull to dominate his own party means he will struggle to stay on top, even if he wins the election. The bright promise of 2015 is simply a dream unrealised, and now probably unrealisable.

Dr Norman Abjorensen is the author of The Manner of Their Going: Prime Ministerial Exits from Lyne to Abbott.