Currently Britain does not have a national bird, but ornithologist David Lindo believes that should change.
A shortlist of 10 birds has been chosen by online voters on his campaign's website from an original list of 60.
Mr Lindo will close the vote on the day of the general election, 7 May, and ask the new government to officially appoint the winner as national bird.
The RSPB welcomed the initiative and said the lack of a national bird for Britain was a "glaring omission".
Mr Lindo, the self-styled "Urban Birder", told BBC Radio 4's Today programme: "I want to encourage the great British public to vote for the bird that best represents all that is great about this nation."
He hoped the appointment could be "the first act" of a new government, once the dust has settled from "the other election", he told the programme.
The robin has emerged as an early favourite, but Mr Lindo, who is backing the blackbird, told Today: "People consider the robin as a British bird - but [like] a lot of our native birds... some of the population move south to Iberia for the winter and are replaced by immigrants from the continent.
"So the robin you see in your back garden during winter is not necessarily British born."
And he added: "It is quite a violent bird."
A first round of polling on the campaign's website received 70,000 votes.
One of England's rarest birds, the hen harrier, is something of a surprise contender, according to Mr Lindo.
"I was expecting 10 garden birds in the list," he said, adding that the original pool of 60 candidates included favourites from literature and song such as the turtledove, nightingale and skylark - all of which have dropped out of contention.
The hen harrier, which was the subject of a recent campaign because it had been the target of illegal hunting, was down to just one breeding pair a couple of years ago  and "may already be extinct", he said.
The robin is sometimes mistakenly thought of as the nation's official bird, the RSPB said, after it was given the title unofficially by some enthusiasts in the 1960s.
Northern Ireland does not have an official national bird, while the golden eagle and red kite are sometimes regarded as unofficial national symbols of Scotland and Wales respectively.
In December 2013 a petition was lodged by the RSPB for the golden eagle to be recognised as Scotland's official national symbol, but the Scottish parliament voted against the plans after it decided the RSPB needed to do more to show greater support for the proposals.
The RSPB said it welcomed Mr Lindo's initiative in getting people to discuss their favourite birds.
And it said the fact Britain did not already have an official national bird while other countries did was a "glaring omission".
Grahame Madge, spokesman for the RSPB, said: "It's opened people's eyes to birds, which is raising awareness. As an organisation we are really behind him.
"It seems most other nations have pipped us to the post in identifying a national bird, and for the UK not to have a national bird when we are a nation of bird lovers does seem to be a glaring omission."
The shortlist, in pictures:
1. Mute swan
2. Red kite
3. Hen harrier
4. Puffin
5. Barn owl
6. Kingfisher
7. Wren
8. Robin
9. Blackbird
10. Blue tit
Votes can now be cast in an online poll to choose what could become Britain's first national bird.