When John Horgan and Andrew Weaver first announced their alliance to form the next government of British Columbia, the NDP and Green leaders returned several times to the sport of rugby.

The day before the announcement, in late May, the two had sat together to watch Canada play in an international tournament. Mr. Horgan and Mr. Weaver love the game and both played rugby when they were younger. During the NDP-Green talks, conversation about the sport offered a break from the political negotiations, a topic on which they strengthened a personal connection. And when unveiling their deal, Mr. Weaver, in an aside, teased Mr. Horgan: In the late 1970s, Mr. Weaver's high school in Victoria, Oak Bay, routinely trounced Reynolds Secondary, where Mr. Horgan attended.

The history of rugby in British Columbia's capital stretches to the earliest days of the province, back in the 1870s when the British brought the game over from England. Rugby thrived in the city's temperate climate. In recent years, the Victoria region has been home to Canada's national women's and men's teams. The game, and competitive sports more broadly, has helped shape the values and passions of Mr. Horgan, NDP Leader and premier-designate, and Mr. Weaver, Green Party boss and kingmaker.

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Mr. Horgan, as a teenager at Reynolds, was more of a basketball and lacrosse player but was pulled in to play rugby in Grade 11. Mr. Horgan was 6-foot-2 and 180 pounds at the time – and fast. "If you could run, they gave you a jersey," remembered Mr. Horgan. "They wanted me to have the ball and run."

It was mostly in a losing cause. "We were never very good," recalled Mr. Horgan's coach, Georges Bombezin.

At Trent University in Peterborough, Ont., Mr. Horgan played basketball and later picked up cricket while at graduate school in Australia. Of rugby, he's been a lifelong fan. The sport's core values – a hard-knock game played without protective equipment that forges strong bonds between teammates and opponents – have always resonated.

"Rugby's the toughest-ass game going but afterwards, there are genuine hugs," said Mr. Horgan. "There is something that separates it from other sports. Honour is the key. Absolute respect for your opponent."

Mr. Horgan, 57, is two years older than Mr. Weaver. The two did not vie against each other on the rugby field. These days, rugby and sports have served as a bridge between the two men. They occupy a similar part of the political spectrum and have often been painted as acrimonious, during the past several years in the legislature and through the tight spring election campaign. Stories in the news continue to latch on to potential divisions between their parties. But the two men describe politics much like rugby: fought intensely but following the final whistle, there does not have to be lingering hostility.

"Anyone who has played sports has a common bond," Mr. Weaver said. "Particularly if you've played it for quite some time and were competitive when you've played. You never lose that. And there is no sport where you get the sense of camaraderie that you get with rugby. I've played lots of sports but rugby is special. You play with such intensity. You can lose your temper. But afterwards, you'll go for a beer with the person you had a scuffle with. You let it all go."

Mr. Weaver played rugby more extensively than Mr. Horgan, starting in high school and on into university. During Mr. Weaver's time as a graduate student at Jesus College at Cambridge University, he was on the same squad as Prince Edward, youngest son of Queen Elizabeth II. The experience was unusual, said Mr. Weaver. "You weren't just playing with him." A bodyguard was also on the field – and Fleet Street paparazzi on the sidelines.

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Mr. Weaver suffered the rigours of rugby, from a broken nose to a blown knee. His rugby days ended back home at UBC. He broke his right ankle when tackled during a game and it didn't fully recover. Later, working in Australia, Mr. Weaver took up cricket, like Mr. Horgan did.

Rugby is not new at the legislature in Victoria. Dave Barrett, NDP premier from 1972 through 1975, played for the local Crimson Tide club. Sports are a common thread among political leaders, to varying degrees of skill. Don Getty, premier of Alberta from 1985 to 1992, helped quarterback the Edmonton Eskimos to a Grey Cup in 1956. Others focused off the field. Stephen Harper, when he was prime minster, published a historical book about an early era of hockey. In the United States, golf is a mainstay of the White House. Barack Obama, when he became president, had a full basketball court installed there. Richard Nixon, in his time, had a bowling lane built in the basement.

In B.C., the previous Liberal government was an important backer of the growth of rugby in the province. It provided money and backing for the annual HSBC World Rugby Women's Sevens Series event in Langford, near Victoria, and the men's event in Vancouver. Steve Thomson, a former Liberal minister who was speaker for eight days in late June, briefly played for Canada's national rugby team in the early 1980s.

Rugby and B.C. politics seem particularly entwined in recent weeks. At the women's tournament in Langford in late May, when Mr. Horgan and Mr. Weaver watched some matches together, on the other side of the stands sat B.C. Lieutenant-Governor Judith Guichon, a guest of Rugby Canada. Ms. Guichon came to the fore last week when she accepted the resignation of former premier Christy Clark and asked Mr. Horgan to form a new government.

The sport runs deep in the provincial capital, knows Gareth Rees, who grew up there and became one of Canada's great players and the first Canadian to enter the World Rugby Hall of Fame. Mr. Rees's dad, Alun, emigrated from Wales and helped shape the sport in Victoria, co-founding the Castaway rugby club in 1965.

"There's a passion for the game and a knowledge for the game," Mr. Rees said.

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Mr. Rees observed how the values of rugby can be valuable in the political arena.

"The ability to be strong but to work with other people – it's the nature of rugby," Mr. Rees said. "Those values are there. Those skills are pretty useful."

For Mr. Horgan, there's fun, too.

"The rugby players always had more zest," Mr. Horgan said. "There's no other way to describe it. The enthusiasm for life, and the game."