Until yesterday, Labor was anxious about its poor polling but calm and resigned to Rudd leading the party to the election.

But a report in the Herald yesterday transformed sentiment. The article revealed that Rudd's chief of staff, Alister Jordan, had been discreetly sounding out caucus support for him. This implied Rudd did not fully trust Gillard's public assurances that she was not interested in challenging him.

This disclosure angered Gillard and some Gillard supporters who began to agitate to tear down Rudd and install her. The feeling was that Gillard and the party had been loyal to Rudd, but Rudd was not dealing with her in good faith.

The sudden anger ignited the underlying anxiety in a highly combustible combination.

Gillard has been deeply reluctant to move against Rudd and until yesterday rebuffed pleas to stand. For weeks she has been urging colleagues to remain calm. Although she is ambitious for the top job, she has been keen to avoid a premature burn-up of a first-term prime minister.

The Rudd-Gillard team was a pragmatic factional alliance forged to unseat Kim Beazley. The underlying architecture of that alliance fell into disarray yesterday even though the leadership duo remained intact.

If Rudd survives this splintering, he will have been weakened and his leadership will be dogged by the impression that he remains in the leadership at the pleasure of his deputy.

Rudd's popularity collapsed in April and May, falling 18 percentage points. A Herald/Nielsen poll this month put Labor unequivocally in a losing position for the first time since Rudd took the leadership in 2006.

While several factors seem to be responsible, Rudd's decision to walk away from the emissions trading scheme appeared to transform perceptions of him. Although Gillard was a party to the decision, her strong personal standing seems untouched.