Peter O'Neill has been formally invited to form Papua New Guinea's next government.
Mr O'Neill, 46, arrived at Government House in Port Moresby about 3.30pm on Wednesday where, addressing him as Prime Minister, Governor-General Sir Michael Ogio invited him to form the government after his People's National Congress party won 27 out of 111 seats in the national parliament during the recent election.
"In the name of the people of Papua New Guinea I invite you to form a government," governor general Ogio said.
However, Mr O'Neill's former deputy, Belden Namah, has placed a newspaper advert urging MPs to form a government with him instead.
Mr O'Neill formed a surprising coalition of about 80 MPs once the results of the delay-marred and internationally-criticised election became clear.
He gained the backing of Sir Michael Somare, the long-time prime minister whose job ended when Mr O'Neill and Namah formed an anti-Somare coalition in August last year.
At Wednesday's ceremony Mr O'Neill was joined by coalition heavyweights Don Polye and former prime minister Sir Julius Chan.
Also present was Australian High Commissioner Ian Kemish and Deputy High Commissioner Margaret Adamson
"I accept this with invitation with a lot of humility," Mr O'Neill told reporters.
"We went to the election with a clear set of policies. Those policies have now been put into a working document and we will all work as one team."
A day shy of a year later, the political team-up between Mr Namah and Mr O'Neill is well and truly over.
Mr Namah is appealing to MPs to join him before Friday's scheduled vote for the parliament to elect Mr O'Neill as prime minister.
"I would like to remind every Papua New Guinean, especially the re-elected and newly elected leaders, that governments are formed on the floor of parliament," Mr Namah said in an advertisement in the Post Courier newspaper.
"I am prepared to discuss and to offer the position of Prime Minister in the interest of our people and our country."
At his camp in Kokopo in New Britain province, the former soldier, prisoner and deputy prime minister is understood to have fewer than 20 MPs at his side.
Mr O'Neill has frequently denied in the local press that his temporary political headquarters in Alotau is a camp - an almost political tradition in PNG where MPs are locked down for a period until a government is formed.
One recently elected MP, former Trade Union Congress president Michael Malabag, said a meeting at Alotau was a government planning session.
"I took part in constructive planning discussions within the Alotau Camp on issues close to my heart," he said on Facebook, before listing a raft of discussion points, including the establishment of an independent commission against corruption.
Electoral commissioner Andrew Trawen has said 105 out of PNG's 111 seats of parliament have been declared.
Election officials have until August 8 to finalise election writs.