He's known as friendly and chatty, but he can get loud and passionate on the legislature floor when fielding questions from the Progressive Conservative Opposition.
Ashton has been around long enough that he, too, has spent time on the opposition benches.
With the NDP in power, he has had a variety of cabinet roles, including transportation, labour and water stewardship. But he has never been given the big portfolios of health, justice, finance or education, and has always been something of an outsider. When he first ran for the leadership in 2009, none of his fellow cabinet ministers stood with him.
At 59, Ashton is hoping the second time is the charm as he vies again for the top job. He has positioned himself between Greg Selinger, who won the 2009 race, and Theresa Oswald, one of the caucus members who launched a revolt against the premier and sparked Sunday's vote.
The outsider is now aiming to be unifier.
Ashton did not take part in the public rebellion against Selinger. While his critics say he has always had an eye on the premier's job, he says he has been loyal and has kept caucus disputes secret.
"It's been tough ... for a lot of us watching us move (away) from the disciplined approach," he says of the dissent that erupted last fall. "The real fight is with the Tories, and if we're divided after March 8th, I tell you that's not going to be good for us."
Ashton was introduced to politics early, partly via the labour movement, and continues to be a staunch ally of unions.
Born in England, his family moved to Thompson, Man., when he was 11.
After studying political science and economics, and serving as president of the University of Manitoba students' union, Ashton returned to Thompson and worked briefly in a mine.
Working underground was an eye-opener.
"You would get the orientation ... 'Over there is where three guys died back in the '60s. We don't mine that area anymore,'" he recalls. "A lot of the people I worked with ended up on long-term disability, workers comp or in major accidents."
Soon after he started, the miners went on strike. Ashton and others protested on the steps of the legislature in Winnipeg. A provincial election was called and Ashton, who had taken out an NDP membership and joined the United Steelworkers, won a seat. He was 25. He's been re-elected in Thompson ever since.
He gained a profile in 1996 when the Progressive Conservative government pushed through a law to privatize the Crown-owned telephone utility. The legislature erupted into chaos as the government changed procedural rules to pass the bill.
At one point, when Speaker Louise Dacquay refused to let the opposition speak, Ashton stood in front of her and accused her of "destroying this legislature."
In recent years, he has become the face of flood protection in Manitoba, briefing reporters sometimes daily during the province's notorious spring flood season.
Ashton's political passion runs in the family. His daughter, Niki, is the NDP member of Parliament for the Churchill riding.
While a lot of cabinet support has gone to his competitors in the current race, Ashton has focused on selling memberships and bringing new people to the party.
He was so effective at it in 2009, there were accusations from some Selinger supporters that Ashton had brought in many recent immigrants who were not committed New Democrats.
Ashton has been endorsed by the United Steelworkers and other unions and has promised labour-friendly measures such as more personal-leave days for public-sector workers.
He finished with one-third of the vote in 2009, but predicts things will be different this time.
"I've won nine elections, but I learned more from the one I didn't win — 2009. It's not that you don't do everything well, you know, or you've done something wrong. It's just sort of a combination of things.
"You learn from experience."