ABC Online... Greens leader Bob Brown says the party may supersede one of the major parties within 50 years.
Mr Brown told The Australian newspaper on Saturday he believes the Greens are in the same position the Labor Party was 100 years ago.
He says the Greens hold views that are widespread throughout the community.
The Greens are closer to the true sense of the word liberal than the Liberal Party, he says.
"I would think the Greens are as close as an American would think anyway to the true word liberal," he said.
"And it may well be the liberals that will succeed.
"I think Tony Abbot is a caricature of a liberal, and the Greens are true liberals."
Opposition Leader Tony Abbott says he can understand why the Greens could one day supersede the ALP as a mainstream political party.
"Julia Gillard said 12 months ago that the Government had lost its way and plainly it's gone from bad to worse since then, so I can understand why the Greens think all of a sudden they are competitive with the Labor Party," he said.
"Obviously [if] you look at the way this government has run over the last nine months, Labor might be in office, but the Greens certainly seem to be in power."
Mr Abbott says Mr Brown is almost the co-Prime Minister of Australia with the Greens now holding the balance of power in both houses of Federal Parliament.
The Greens obtained the balance of power in the Senate on Friday, with four new Greens senators who were elected last year starting their terms.
The Greens now hold nine of the 76 seats.
The rest of the Senate is comprised of 31 Labor members, 29 Liberals, five Nationals, one independent and one senator from the Democratic Labor Party.
That means no side of politics can win a majority of 39 votes in the Upper House without the Greens.
