Papua New Guinea's parliament is expected to decide on Tuesday whether to extend a ban on votes of no confidence from 18 months to 30 months in a bid to ensure political stability.
Prime Minister Peter O'Neill is expected to secure about 80 votes to pass the law, which will ban votes of no confidence in the government until 30 months after it is first elected.
The bill passed its first test in November with 102 votes, but in late January opposition leader Belden Namah - who at first praised the bill - announced the opposition was withdrawing its support.
"It goes against the spirit of the constitution in that it restricts or removes the parliament's function of keeping the executive government accountable to the parliament," he told local media on Sunday.
"We will not support the bill and we call on the members of parliament not to vote for the bill."
A spokesman for Mr O'Neill said he expected the bill to pass despite the protests of the 15-man parliamentary opposition.
At the first passage of the bill in November Mr O'Neill warned that constantly shifting parliamentary loyalties meant governments were planning for survival, instead of implementing policies.
"It's no wonder our health and social indicators have been in decline, and infrastructure like roads and bridges and ports are in (an) appalling state, our schools and education facilities are run down.
"We cannot allow this to continue."
AAP understands Mr O'Neill needs 74 votes to pass the bill into law.
Votes of no confidence have been a thorn in the side of successive prime ministers since PNG gained independence from Australia in 1975.
PNG's first prime minister, Sir Michael Somare, lost the top job in 1980 after a vote of no confidence.
In 2003-04, the Somare government failed in its bid to have the so-called grace period extended from 18 to 36 months.
He was PNG's longest-serving prime minister after a nine-year run, but was deposed by parliament on August 2, 2011, in favour of Mr O'Neill.
That move sparked a constitutional crisis that ended in mid-2012 after a general election which put Mr O'Neill back in the prime minister's seat with the backing of about 94 of PNG's 111 MPs.
