Andrew Weaver is barely out of his car when he is stopped by a passerby asking if he has a lawn sign she could put up. The Green Party Leader is happy to oblige, opening his trunk to hand over a small poster of himself that is ubiquitous in the upscale neighbourhood of Oak Bay that he has represented since 2013.

When he finally takes a seat in the Demitasse café, the 56-year-old academic-turned-politician is still on a post-debate high. There is a widening consensus that of the three leaders that took the stage in the only televised debate of the campaign, it was the Green Party Leader who likely made the greatest inroads with viewers – many of whom had never heard of the man before.

He admits now that he found the event intimidating. Actually, "awe-inspiring" is the word he used. He confesses to feeling "light-headed" moments before he had to give his opening statement. He thought he might faint. He had trouble reading the words of his script. It was easy to discern his nervousness in the tremor of his voice. "It was something so far out of my traditional comfort zone I can't tell you," Mr. Weaver would recall, less than 24 hours after the debate.

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He got through his opening monologue and soon found himself in a one-on-one debate with Liberal Leader Christy Clark on the topic of housing. It was an issue he felt passionate about; it was also one on which he felt Ms. Clark was most vulnerable. He did well. And from there his confidence seemed to grow. This fact was evident in his exchanges with NDP Leader John Horgan, which were testy. This was in stark contrast to the only other debate the three leaders had engaged in a week earlier, on radio, one in which Mr. Weaver chose to ignore Mr. Horgan completely.

This debate would be different. He felt he would and could go after the NDP Leader in a way he couldn't go after Ms. Clark.

"Look, I'm a big guy, and John's a big guy," Mr. Weaver said, sipping a coffee. "Ms. Clark is a much smaller woman and I had to be mindful of that. A big guy verbally attacking her could easily look like a bully. So I had to find a way of interrupting her in a respectful way. I didn't have the same concerns with Mr. Horgan."

At this point, Mr. Weaver has his coffee interrupted by a constituent. "I'm sorry, but I just wanted to say how impressed I was with you last night," the woman says. "Everyone I've talked to says the same thing. You were just so clear and concise with your answers and really made it obvious why there needs to be a change in government."

The Green Leader is delighted by the fortuitousness of the woman's timing.

"I'm being interviewed by The Globe and Mail on this very subject right now," he beams. "On Vancouver Island we could win every seat now. Our polling numbers are going through the roof."

If Andrew Weaver was feeling positive about his party's chances of a breakthrough in this election before Wednesday's televised debate, it's fair to say he is absolutely buoyant now, and convinced we are about to witness history on some scale. He won't say – on the record at least – how many seats he thinks the Greens will win on May 9, but through various hints he drops throughout our hour-long conversation you get the impression that if his party wins less than 10 he will consider it a major disappointment. I mean, he's talking out loud about "running the table" on Vancouver Island, which has 14 seats. That is cheek.

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On the other hand, if the polls are correct, the Greens do seem poised to do some real damage on the Island. While someone like Mr. Horgan might be safe in his Esquimalt riding, Mr. Weaver believes the party could take down someone like former NDP leader Carole James in her riding of Victoria-Beacon Hill. The Greens received nearly 9,000 votes last time.

"There is change in the air," Mr. Weaver says. "I can smell it."

The noted climate scientist says the last four years in the legislature have opened his eyes to just how broken politics is in B.C. The two main parties are so deeply entrenched in the existing system they can't allow themselves to fix it; they are attached to the status quo in a way the Greens aren't.

Mr. Weaver says the system is deeply corrupt too. And there is no better example of that than the province's disastrous campaign finance laws, a regulatory free-for-all that the governing Liberals exploit to enormous benefit. The Greens are the only one of the three parties that has refused to accept corporate and union donations. The NDP has vowed to ban them if they get in power, but until then is continuing to accept them.

That, Mr. Weaver says, was a critical mistake.

"If the NDP had done what we did on this they would have won the election," Mr. Weaver says. "Of that, I have no doubt. But they lost all their credibility on the issue; they became as bad as the ones they were criticizing and so they lost the moral high ground. It was a critical mistake."

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Between now and the end of the campaign, Mr. Weaver will be all over the place. Green support is exceptionally strong on the Island, but there are intense pockets of strength in the Kootenays, the Cariboo and the Okanagan, as well in parts of Metro Vancouver. He won't feel guilty if the Liberals get back in because the Greens took seats away from the New Democrats.

"Look," he says. "The NDP had the last 16 years to make their case for government and they failed. They don't own anyone's vote and yet there is this sense of entitlement that they have that if it's not the Liberals it has to be them.

"No it doesn't. They had their chance to inspire and the failed at it. Now it's our turn."