Never give up, says Shorten after big wins

Bill Shorten says success in a Super Saturday of by-elections is a signpost to a change in federal government.

The Labor leader was under pressure from a range of sources, from the prime minister to disgruntled caucus colleagues, to ensure the party performed well at five by-elections held on Saturday.

There was also speculation he could be dumped as leader and replaced by Anthony Albanese.

Two weeks ago Malcolm Turnbull declared it as a contest of leaders.

"The head-up, the contest is between me and Bill Shorten as the prime minister and the opposition leader," Mr Turnbull said at the time.

It appeared on Saturday night Labor was likely to win four of the by-elections with the Centre Alliance's Rebekha Sharkie holding on to her former seat of Mayo.

"Four from four," Mr Shorten declared at a Labor function in Longman, standing next to winning candidate Susan Lamb.

Mr Shorten said the party's rank and file members had put their shoulder to the wheel.

"Tonight is another signpost into the destination that matters for Australians - a Labor government after the next general election," he said.

"We understand unlike our critics and opponents it is never about us - it is always about you, the people of Australia."

Veteran Labor strategist Bruce Hawker said it would bolster Mr Shorten's leadership.

"Labor has done very well tonight The person who would be really disappointed will be the prime minister - he thought he could kill Bill tonight and he didn't."

Labor frontbencher and Shorten ally Richard Marles put it simply: "Bill won tonight."