The shifting sands of politics in the Melanesian nation appear to be giving way under Mr Manele, who will face a no-confidence motion when parliament resumes on Tuesday.
Mr Manele succeeded Manasseh Sogavare as prime minister following an April 2024 election, with Mr Sogavare becoming finance minister in a three-party coalition following government formation talks.
A year on, Mr Sogavare led a walkout of almost half the cabinet and other government MPs last week, citing instability and weak leadership.
The wily 70-year-old has since formed a new grouping including Opposition Leader Matthew Wale, which claims a parliamentary majority and intends to vote Mr Manele out.
Pacific analyst Richard Herr said frenzied negotiations between MPs would be taking place ahead of Tuesday's vote.
"Everyone seems to be holding their breath ... anything could happen," he told AAP.
Central to the uncertainty is whether the grouping can unite behind a new choice for prime minister.
It is unclear whether Mr Wale, Mr Sogavare or another option will emerge as leader and presumptive prime minister in waiting.
The no-confidence motion has been moved by Central Honiara MP Gordon Darcy Lilo, another ex-prime minister.
Dr Herr said the new grouping also had both pro-China MPs, such as Mr Sogavare, and those who weren't supportive of the 2019 diplomatic switch from recognising Taiwan to Beijing, such as Peter Kenilorea Jr.
A lack of agreed leadership or positioning would leave a new coalition open to the same sort of collapse Mr Manele's government has suffered in the last week.
"It doesn't seem on the face of it a particularly solid coalition," Dr Herr said.
Mr Sogavare denies seeking the prime ministership but said he would take it if offered.
Bradley Tovosia, who was Mr Manele's deputy PM before resigning last week, said Mr Sogavare was the instigator of the crisis, saying he "wasn't a happy man" after missing out on the prime ministership.
Should Mr Sogavare return, it would be a fifth stint as the country's leader at age 70.
In the mean time, Mr Manele has gotten on with the job, swearing in new ministers, and insisting his government for national unity and transformation (GNUT) coalition can survive.
"The resignation of senior ministers is a blessing in disguise," he told local journalists at a press conference on Friday.
"It is the dawn of a new era to usher in fresh, young and energetic leaders who are willing to take up the challenge to lead our people and country. GNUT door is open."
In parliament last week, both Mr Wale and Mr Manele called for calm among Solomon Islanders amid the political crisis, given previous impasses have led to unrest.
Local newspaper Island Sun reports the police have indicated a low chance of security issues.
"Despite this motion, there is no potential threat coming or being picked up by our intelligence ... I would like to thank the people," Royal Solomon Islands Police Force commissioner Mostyn Mangau said.
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