Peter O'Neill, one of two rival prime ministers in Papua New Guinea, says he is now in charge of the strife-torn country.
Dozens of police loyal to Mr O'Neill have been flown to the capital from elsewhere in the country to secure government buildings.
Mr O'Neill's rival, Sir Michael Somare, has not been seen in public for days.
Trouble flared when Sir Michael came back from a long stay in Singapore and claimed he was still prime minister.
He was sworn in by the governor general on Wednesday, but Mr O'Neill responded by installing another governor general and having himself reinstated.
The country now has two prime ministers, two cabinets, two governor generals and two police chiefs.
But analysts say Mr O'Neill now seems to have the upper hand.
The police ejected Sir Michael from the prime minister's residence earlier.
Officers also secured a state-run printing press that then published a newspaper proclaiming Mr O'Neill as the only legitimate prime minister.
And reports say a group of police officers that was guarding Sir Michael has defected to the other side.
Mr O'Neill told reporters outside the prime minister's residence: "There is only one government in this country. There is only one government mandated by the people through its parliament."
Sir Michael, who has been a major figure in PNG's politics for 50 years, was flown to Singapore for treatment for a serious illness earlier this year.
During Sir Michael's absence, Mr O'Neill was installed as prime minister. It was widely believed Sir Michael had stepped down voluntarily.
However, this week the country's supreme court ruled the takeover illegal - a decision later backed by the governor general.
But Mr O'Neill appears to have the support of most MPs and the police.
So far, witnesses say the political crisis has not caused any social unrest, with people in the capital Port Moresby going about their business as normal.