The shock resignation of one of Bill Shorten’s rising stars has set up a crucial pre-election contest that is set to test Labor’s prospects in  the West and the electoral potency of next week’s budget.

Labor’s shadow consumer affairs spokesman and Perth MP Tim Hammond revealed he would quit politics on Wednesday, citing the toll it had taken on his wife and three young children.

“A lot of my colleagues on both sides of the divide make it work,” he said. “But I’ve just got to be really honest, I’m not one of them.”

The decision triggers a byelection in his seat of Perth, which covers the city’s CBD and inner suburbs north of the Swan River.

Political experts said the contest would provide an early test of Labor’s support in WA, where it underperformed in the 2016 election, with the party expected to healthily increase its 3.3 per cent margin.

It will also provide the first electoral gauge of the Turnbull government’s May budget, which is expected to include pre-election “goodies” such as personal income tax cuts and massive infrastructure spending.

On the same day Mr Hammond resigned, a ReachTel poll found the government trailing Labor 48-52 on two-party terms, with Malcolm Turnbull increasing his lead as preferred PM.

Announcing his decision on Wednesday, Mr Hammond, 43, stressed he had been reluctant to cause the “dreadful inconvenience” of a byelection, but could not wait until Mr Turnbull called the election.

Given sitting governments usually suffer a swing against them during byelections, Labor would be expected to increase its margin, WA political expert Dr Ian Cook told The New Daily.

A byelection date will not be known until Mr Hammond officially hands his resignation letter to Speaker Tony Smith.

But the resulting poll will likely cost taxpayers in excess of $1 million, with previous byelections in North Sydney and Canning in 2015 costing $1.7 and $2 million respectively.

Dr Cook, from Murdoch University, said he would not be surprised if the Liberals sat the race out, saying the party had “a lot to lose” and would not want to waste resources on a seat it was unlikely to win.

“There’s that fear that there will be a big swing to Labor and it would then swing everyone to Labor,” he said.

WA Liberal state director Sam Calabrese said the party was considering its options.

“Nominations are currently open for a number of federal electorates, including Perth,” he said in a statement to The New Daily.

“The party will continue to consult with local membership in relation to the upcoming byelection.”

On the Labor side, the party’s WA state director Patrick Gorman is expected to nominate for the seat.

Canberra a challenge for WA politicians

An emotional Mr Hammond said on Wednesday he had tried to make his new career work, but simply could not go on.

Mr Hammond has three young children with his wife Lindsay, including a six-month-old, and was elected at the 2016 poll.

His Labor colleagues and political opponents greeted his departure with sadness, with many noting the difficulties faced by WA politicians, who travel more than four hours by plane to Canberra.

Mr Shorten said he was “disappointed” Mr Hammond would not be part of Labor’s next caucus but was “glad he’ll be with the people he cares about most in this world”.

Finance Minister Mathias Cormann, who considered Mr Hammond a friend, paid tribute to the Labor MP, noting that “public service as a federal politician from WA is tough on our families”.

Once considered a possible Labor leader, Mr Hammond immediately ruled out a future return to politics, saying he would resume his previous career as a barrister.

Former opposition frontbencher Kate Ellis announced last year she would resign at the next election to spend more time with her young son.

Labor is also facing the possibility of three other byelections over citizenship, subject to the High Court’s interpretation of ACT senator Katy Gallagher’s case.