Tasmanian Liberals say there are rumblings within the party to drop veteran Eric Abetz from the top spot on the Senate ticket in favour of his apprentice, Jonathon Duniam, by the next election.

Key points: Conservative Liberal senator Eric Abetz was elected to parliament in 1994, but he has not held a portfolio since 2015

Conservative Liberal senator Eric Abetz was elected to parliament in 1994, but he has not held a portfolio since 2015 Inside sources say the party believes only two seats are assured in the next half-senate election and some want to see Senator Abetz's top spot on the ticket given to Jonathon Duniam

Inside sources say the party believes only two seats are assured in the next half-senate election and some want to see Senator Abetz's top spot on the ticket given to Jonathon Duniam The election is not for several years, but the ABC understands there are concerns preselection could take place earlier than usual

Senator Abetz, Senator Duniam and Senator Wendy Askew will battle it out for a priority spot on the 2022 half-senate election ticket.

The party believes only two seats are assured, and some members are worried about the optics of dropping Senator Askew — one of three Tasmanian women representing the party in Canberra — to the difficult-to-win third spot.

Tensions are rising among the Tasmanian Liberals ahead of each electorate's annual general meeting over the next fortnight.

The party's senate preselectors will be chosen at the events.

Although the election is not for several years, several Liberal sources say Senator Abetz and Senator Duniam are worried preselection could take place earlier than usual "to rip the band-aid off" and the pair have been working the phones to try to secure their positions.

Senator Abetz and Senator Duniam both declined to comment.

Both men hold conservative Liberal beliefs, but Senator Duniam voted in favour of same-sex marriage in 2017 — something Senator Abetz has spoken strongly against.

While all sides agree Senator Abetz should not be underestimated, moderates have backed Senator Duniam as their preferred face for the Tasmanian Liberals.

"The argument is, renewal is needed," one source said.

Prior to being elected, Jonathon Duniam (left) spent four years as an adviser to Eric Abetz. ( ABC News: Matthew Abbott )

Senator Duniam holds an elevated position within the party, having been appointed Assistant Minister for Forestry and Fisheries as well as Regional Tourism after the May federal election.

Senator Abetz was barely seen during Prime Minister Scott Morrison's many visits to Tasmania during the same campaign and has not held a portfolio since 2015.

He had backed now-Lyons state MP John Tucker to replace David Bushby in the senate after he stepped down in January but was gazumped by state Infrastructure Minister Michael Ferguson's pick, Senator Askew, who is Mr Bushby's sister.

Senator Abetz has been in the parliament since 1994 and will put his hand up for a fifth term.

Senator Duniam was an adviser to Senator Abetz from 2005 to 2009 and now-Premier Will Hodgman's deputy chief of staff from opposition in 2010 to 2016.

He was elected to the Senate the same year.

The push among some for generational change comes as the Tasmanian Liberals hunt for a new director after Sam McQuestin was announced head of the party's Victorian branch.