They say you should never work with children or animals – but on day four of the election campaign, Bill Shorten did both.

The Opposition Leader celebrated his 49th birthday on Thursday watching primary school students program robots and patting cows in Australia’s beef capital, Rockhampton.

The kids at Frenchville State School greeted him with a “happy birthday” sing-along while the cattle were also well-behaved.

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But the best present of all was wife Chloe, who made her debut on the trail as it rolled into the key central Queensland seat of Capricornia.

She brought some colour and warmth to the campaign as she stepped off the Shorten bus in Rockhampton dressed in a bright yellow pencil skirt with matching pointed stilettos.

She joined Mr Shorten on a tour through the primary school, sitting at tiny tables to meet and greet the awe struck students and crouching down on the floor to watch them play robots.

When it came time to meet the cattle, she asked if she could have a selfie with them, for her daughters.

“I try to teach my kids about what it was like to grow up spending a lot of time in the country,” she said.

Bill Shorten presses the flesh on the campaign trail in Townsville. Photo: AAP

Asked by reporters whether he received a birthday present, the Opposition Leader smiled and looked to his right.

“My present is standing right next to me.”

Her arrival was good timing for Mr Shorten, who faced his toughest grilling on the trail so far, following fresh reports of division in the party over asylum seeker policy and the dumping of Labor’s candidate for Fremantle for failing to declare his criminal past.

Capricornia is a crucial win for Mr Shorten.

It’s held by Liberal National MP Michelle Landry by a very slim margin of 0.8 per cent, but has traditionally been a Labor seat.

Labor’s candidate there, Leisa Neaton, is the latest in a growing list to have raised concerns over the party’s offshore processing policy on asylum seekers.

But she insists she backs the party policy.

Mr Shorten has declared the Labor party the real country party of Australia, pledging $1.8 billion of Labor’s promised $3.8 billion boost for school funding to regional schools.

Mrs Shorten will remain on the trail for a few days, and will make appearances over the next eight weeks.

She’s also been busy doing some campaigning of her own in western Sydney and Bendigo.

But on Thursday, the pair took some time out to share a piece of birthday cake together.

-AAP