Incumbent Manasseh Sogavare says he will not be a candidate when Solomon Islands MPs vote for a new prime minister, with his political party backing former foreign minister Jeremiah Manele instead.
The two major opposition parties in the Solomon Islands struck a coalition deal on Saturday as they vie with Sogavare's party to form a government after an election delivered no clear winner.
The April 17 election was the first since Sogavare struck a security pact with China in 2022, inviting Chinese police into the Pacific Islands archipelago and drawing the nation closer to Beijing.
The election is being watched by China, the US and neighbouring Australia because of the potential impact on regional security.
Sogavare announced he would not be a candidate for prime minister at a televised press conference on Monday evening.
He said his government had been "under pressure from the United States and Western allies" and he had been "accused of many things".
"Geopolitics is at play after we made a very important decision in 2019," he said, referring to his government's decision to switch diplomatic recognition from Taiwan to Beijing.
Manele said if he was elected as prime minister he would have the "same foreign policy basis - friends to all and enemies to none".
Election results on Wednesday showed Sogavare's OUR party won 15 of the 50 seats in parliament, while the opposition CARE coalition has 20.
Independents and micro parties won 15 seats, and courting the independents will be the key to reaching the 26 seats needed to form a government.
Sogavare said on Monday his party had support for 28 seats.
MPs are expected to vote on May 8.