Alex Salmond said Alba is “taking a swing” at established parties, as he visited a boxing gym owned by one of his candidates.
The former first minister said he believes pollsters forecasting defeat for new parties will end up with “egg all over their face”.
A number of recent polls have put Alba in single figures on the regional list vote, with some analysis suggesting the party will struggle to elect any MSPs.
Mr Salmond said he was celebrating the reopening of gym facilities as he stepped into a ring owned by Alex Arthur, a former boxing champion and Alba candidate.
Speaking to the PA news agency, Mr Salmond said: “Alba in this campaign are the plucky underdog.
“We’re coming into the ring, we’ve been fours weeks in existence and we’re taking a swing at the established parties.
“We’ve got every hand turned against us in this campaign, the establishment media, the mainstream media, we’re getting blacked out of television.
“But our strength is in the communities around Scotland and that’s what’s going to prevail.”
Mr Salmond added his new party could still break through, saying: “Alba is rising at the present moment and the pollsters are going to end up with egg all over their face.
“There are difficulties in how you measure a new party – because polling is weighted by previous party preferences.
“If you don’t have any previous preferences it’s very difficult to measure a new party.”
Mr Salmond said Alba could win representation in every region of Scotland.
Discussing polling showing an increased vote share for the Scottish Greens, he said: “I’ve got nothing against the Greens but I think their commitment to independence is weak as water.”
He said many in the independence movement wanted to see “urgency” in the campaign, which Alba would provide with a planned motion to begin independence negotiations with Westminster as soon as Holyrood returns.
Independence would inevitably lead to an “administrative border”, he said, adding Scotland should immediately seek European Free Trade Association membership after independence.
He said the economic case for independence needed to be “furnished and burnished” for the current day.
An independent Scotland should move to establish its own currency within months of independence, he said, as the ability to issue debt would be crucial.
He said: “We think now, as opposed to 2014, there should be a clean break settlement between Scotland and the rest of the UK.
“All we’re doing is putting forward a contribution to the economic debate.
“We’re saying you can’t go into a referendum with the same economic policy you had seven years ago when the world was different.”