Former Australian Prime Minister Malcolm Turnbull resigned from Parliament on Friday, triggering a by-election that could bring down the unpopular conservative government.

Disgruntled lawmakers in Turnbull's conservative Liberal Party replaced him as prime minister with his treasurer, Scott Morrison, in a party ballot last Friday. The government has trailed the center-left opposition Labor Party in most opinion polls since the last election in 2016.

Turnbull became the fourth prime minister ousted by his or her own party since 2010. He warned that he would quit Parliament and cause a by-election that could cost the government its single-seat majority.

The by-election in Turnbull's wealthy Sydney electorate could be held as early as Oct. 6. House of Representatives Speaker Tony Smith's office did not immediately respond to a request for comment on Friday.

Turnbull has been criticized by former Deputy Prime Minister Barnaby Joyce for refusing to stay in Parliament until the next election, due in May next year.

Joyce, who fell out with Turnbull over an affair Joyce had with a former staffer, said "people are going to be really disappointed" by Turnbull's decision not to serve his full three-year term.

Morrison on Friday had nothing but praise for his predecessor. "I'm disappointed Malcolm's leaving Parliament and is leaving public life. Malcolm has been a dear and close friend of me for a very long period of time and has served his country well and grandly. As a prime minister, he'll be well remembered I believe over time," Morrison told reporters in Jakarta.

"Right now I just want to send to my friend Malcolm and to [his wife] Lucy and their entire family all my best wishes and all my love," Morrison added.

Turnbull told his supporters on Wednesday that he would resign this week. "I don't want to dwell on recent shocking and shameful events — a malevolent and pointless week of madness that disgraced our Parliament and appalled our nation," Turnbull wrote of his ousting.