North Wales Liberal Democrat AM Eleanor Burnham could lose her seat at next May's election after coming second on the party's regional candidate list.
Wrexham council leader Aled Roberts took the top slot in a vote of party members.
The Lib Dems are likely to take only one seat in the region next year.
Ms Burnham became an AM in 2001 following the resignation of Christine Humphreys.
Ms Burnham was returned to the seat in the 2003 assembly election having been selected to head the party list.
Ms Burnham, a former business adviser and local magistrate, said: "I send my congratulations to Aled on topping the North Wales list for the Welsh Liberal Democrats.
"I know that he will campaign hard and work even harder if elected to represent the people of north Wales.
"I look forward to campaigning alongside him in the months ahead. We will be campaigning hard to get as many Welsh Liberal Democrats representing north Wales in the National Assembly."