Tony Abbott held one of his regular dinners with MPs in his prime ministerial dining suite on Tuesday. Andrew Robb was there, the trade minister who has pulled off the three free trade deals which sit at the top of every list of this government’s achievements.

The prime minister proceeded to aggressively castigate his senior minister – one source said “dump on” him – for the government struggling to “sell” the benefits of its China free trade agreement and because the government’s taxpayer-funded advertising campaign to spruik the deal has been slow to eventuate and is not running in the lead-up to the Canning byelection in Western Australia, despite repeated assurances that it is “in the can”.

The Liberal federal director, Brian Loughnane, is also said to have mentioned the prime minister’s “fury” at the absence of these government China free trade ads in the lead-up to Canning next weekend during a meeting of marginal seat MPs on Wednesday. Loughnane conceded to the meeting – apparently getting bigger and bigger as more backbenchers find themselves in the danger zone under the swings predicted in every opinion poll – that the issue was hurting the Coalition in Canning.

It seems that – just as Labor found with its carbon tax advertising campaign – it’s really hard to fit politically potent advertising into the fact-based guidelines for ads that are paid for by the taxpayer. And in any event the point of the government’s $24m campaign is to promote and explain all three free trade deals, not help the government in Canning, even if the result is seen as critical to Abbott’s future. For the record, radio ads are set to start this week, but the television campaign won’t be ready until later this month.

The prime ministerial dressing down came just days after unsourced reports that Robb might be in line to replace former Labor leader Kim Beazley as Australia’s ambassador to Washington, forcing Robb to publicly declare he had no interest in leaving his current ministerial position. And a few days later Robb found himself on the Daily Telegraph’s cabinet reshuffle hit-list. More of that later.

Robb is probably not the government’s best communicator, but he’s by no means its worst, and he has poured every ounce of his energy into his portfolio and in most people’s estimation has done a very good job. Abbott always publicly praises Robb, so the dinner tirade might be put down to deep political frustration. Other sources insist the prime minister’s frustration was directed at the slowness of the ad campaign rather than the minister, who doesn’t actually control the bureaucratic ad approval process. But some in the room certainly saw it as a dressing down. But how dumping on a senior minister in front of a roomful of colleagues could possibly help morale or enhance his or the government’s sales pitch is a mystery to many in the Coalition.

And at least Robb’s efforts at explaining the benefits of the deal go to its detail, rather than thinking that a quick name-change would do the trick, apparently the assumption behind the Coalition’s attempt to rebrand the FTA as a “China export agreement” on Thursday – as if we’d all then forget that Chinese imports are also part of the free trade equation.

But back to the hit list: yet another unsourced newspaper story that the prime minister was planning a big reshuffle of his ministry before Christmas. Phones ran hot on Friday with theories about who was behind the leak and what might have motivated it. The prime minister emerged to insist it was “wrong” and that “reports of end-of-year reshuffles are absolutely a dime a dozen”.

He was certainly right on the second point. Many versions of the same story have run in recent months, most recently in the Australian on 22 August. The assumption within the Coalition is that the prime minister’s office is either behind them, or at least not dissuading their publication. The prime minister’s office denies this. But it seems reasonable to assume that no journalist would even consider writing a story asserting that the prime minister was planning to sack eight named ministers without at least running the proposition past the prime minister’s office, even if the original source of the idea was someone else.

One of the jostling leadership contenders maybe. Perhaps one who was miffed that Abbott was refusing to shift Joe Hockey from the treasury portfolio and install them instead.

And such stories could work in the prime minister’s interests. The threat of a reshuffle might be enough to give unhappy ministers pause for thought, and the prospect might settle those waiting in the wings and worried the government is about to get turfed out before they ever get their feet under the cabinet table.

And the Tele yarn did list eight ministers facing demotion and 11 set for promotion, which wouldn’t really work when you think about it.

Whatever its source, the attack on Robb and the constant leaking and speculation about ministerial positions is evidence that the internal positioning and tensions caused by the Coalition’s entrenched poll position and leadership struggle is overtaking the broader interests of the government and the nation.

The cabinet could not make a decision on competition law two weeks ago – an issue considered of vital importance by both big and small business – because ministers held strong and opposite opinions and the government apparently could not risk the fight. It was deferred indefinitely, leaving small business supporters of the legal change and big business opponents locked in an endless cycle of lobbying and uncertainty.

Last week’s cabinet meeting did not discuss the government’s political situation, even though it was held on its second birthday and after a new poll showed its primary vote remained 6.6% lower than when it was elected. That chat was deferred to the post-cabinet dinner, which several ministers skipped.

The truce that was supposed to last at least until after the Canning byelection has not held and ministers readily concede the current situation is not tenable. They’re just not clear how or when to change it.