Greens Candidate for the Senate Simon Sheikh.

Greens candidate for the Senate, Simon Sheikh. Photo: Jay Cronan

Greens' candidate Simon Sheikh says the party's polling in Canberra gives him more confidence for the difficult battle to win an ACT Senate seat in the election.

After his campaign launch at the Shine Dome on Sunday, he strongly criticised Liberal candidate Zed Seselja as the ''captain of team negative''.

The function was attended by about 180 supporters, many of whom have been sent to Canberra's outskirts to galvanise support for the party.

"We are the underdog at this election, there's no doubt about that. But this is a winnable election,'' Mr Sheikh said.

"At the last election the Liberals broke quota by just 38 votes, making this the tightest Senate race in the country.''

Mr Seselja is the former ACT opposition leader who defeated the incumbent, Senator Gary Humphries, to become the Liberals' leading candidate for the Senate race.

Mr Sheikh was critical of Mr Seselja's performance.

"The people of Tuggeranong, for example, are deeply disappointed that at one stage they had the member for Brindabella and the next day he was gone,'' he said.

"So we're appealing to these voters on the issue of trust: if Gary Humphries couldn't trust Zed Seselja, how can Canberra families?

"Zed Seselja is captain of team negative. He's captain of the three-word slogan team and he takes a leaf out of Tony Abbott's book.

"Here in the ACT we are the most intelligent community in the country. At the territory election we rejected the three-word slogan of the Liberal Party. I think we will see the same thing happen here in the ACT [Senate race].''

Mr Sheikh said the polls showed Mr Abbott had a good chance of winning the election.

''But no matter which of the old parties wins, we mustn't be rewarding them for the policies they're taking to this election,'' he said.

"We can't be rewarding them for taking a policy of cutting jobs, so many jobs that it will hurt our community and send it into recession.'' Mr Sheikh predicted the Greens would eventually have a good chance of winning the lower house seat of Fraser, covering northern Canberra.

''It's one of those seats like Melbourne and Grayndler that in time we've got a good chance of winning because we've got strong candidates … our internal polling is showing we're on the up and up here in the ACT,'' he said.

The terms of territory senators end with a general election, unlike state-elected senators who have a six-year term.

The quota to win one of the two Senate seats in the ACT is one-third of the vote.

The Labor Party's strong support means it is assured of one seat, and the Liberal Party has always scooped the other spot.

At the last election the Liberal Party's Senate team won 33.35 per cent of the primary vote. The result was higher in the 2004 and 2008 elections.

In an earlier election, the Liberals' Margaret Reid did have to rely on One Nation preferences to be returned. At the last territory election, the Greens' team in the Legislative Assembly was reduced from four to one.

The survivor, Shane Rattenbury, now a minister in the Gallagher Labor government, said the Senate race gave ACT voters the chance to ''stamp our foot, to make a presence on the national stage - to say, we won't be just ignored in the ACT, we won't be taken for granted, we're not just a safe Labor seat,'' Mr Rattenbury said.

"This Senate seat is winnable. I have been campaigning with the Greens since 1992 and this is the biggest, most professional, most organised campaign there has been.''