The Labor Party’s leadership tensions have been given fresh life by allegations Julia Gillard and key factional supporters were preparing to challenge Kevin Rudd weeks before his eventual overthrow.

Ms Gillard has consistently stated that her decision to take on Mr Rudd was made on the day of the coup in June 2010.

However, ABC1's Four Corners has revealed that senior staff in Ms Gillard's office at the time had started writing the first speech she delivered as Prime Minister at least two weeks before she took power.

In an interview for the program Ms Gillard avoided answering whether she was aware the speech was being prepared.

"Look, I am not surprised that whether it's people in my office or people more broadly in the Government of the Labor Party were casting in their mind where circumstances might get to, of course," she said.

Four Corners also cites internal Labor Party polling in the week before the challenge as proof the campaign was building far earlier.

The polling compared Ms Gillard with Mr Rudd, saying she was more popular with voters, and pointing to negative focus group reactions to the then-leader.

When questioned about the polls, Ms Gillard again appeared to skirt the issue, saying she did not have "specific recall of pages of party polling at the time".

But a partial transcript of the interview released by the Prime Minister's office to ABC News Online shows responses from Ms Gillard that were not broadcast.

On the issue of internal polling, she says: "I take it the implication from your question is that some part of the decision I made was motivated by polling; if that is the implication of your question, that's wholly untrue."

The transcript also shows her stating that she never asked for a speech to be prepared and reiterated that she decided to mount a challenge on the day.

"I'm saying to you I'm not surprised that you're in a position to say that people within government were thinking about alternatives," Ms Gillard said.

"With respect, the headlines of the newspapers were screaming it every day. But in terms of my motivations and when I acted and when I made a decision, I made a decision the same day I acted."

In more bad news for Ms Gillard, today's Newspoll shows she has lost ground to Tony Abbott in the preferred prime minister stakes.

Mr Abbott's support rose three points to 40 per cent while Ms Gillard's slipped the same amount to 37 per cent in the poll, published by the Australian newspaper.

The Coalition's primary vote is up one point to 46 per cent, while Labor's is up two points to 32.

The Coalition still leads Labor 55 per cent to 45 on a two-party preferred basis.

Gaining momentum

Four Corners asserts the US State Department knew a leadership change was gaining momentum.

It states that about two weeks before the coup, Australia's ambassador to the United States, Kim Beazley, was called in to explain to US secretary of state Hilary Clinton what was happening in relation to change in the prime minister's office.

US embassy cables released through WikiLeaks have shown that the State Department had been receiving leaked information on internal ALP politics for months.

Labor right-wing powerbroker Graham Richardson told Four Corners he knew "a week or so" before the change in leadership that a challenge would be mounted.

Mr Rudd did not grant Four Corners an interview.

When the idea of returning to the prime minister's office was put to Mr Rudd he would not say if the idea appealed.

"Well, that's a matter for history," he said.

"I’m a very, very happy little vegemite."

The Four Corners program had been widely anticipated in political circles because of recent fevered speculation that the former prime minister was poised to launch a comeback.

It is likely to trigger another round of questions about the coup and accusations from the Opposition of political instability and division in government ranks.