Abetz: Turnbull needs to listen to backbench more

PRIME Minister Malcolm Turnbull will need to listen to his backbench more after the "kick up the pants" voters gave the Coalition at the ballot box two weeks ago.

That was the message from conservative backbencher and former Leader of the Government in the Senate, Eric Abetz, on ABC Radio on Thursday morning.

The warning from Senator Abetz came as Mr Turnbull weighed up who would be in Cabinet after a pledge to the Nationals on Wednesday to boost their Cabinet seats to six.

Sen Abetz said the election result should have the Coalition leadership asking "Why did we hemorrhage so many votes?"

He said it was a "kick up the pants" and "the barest of victories" - and a signal Mr Turnbull had to listen more to the backbenchers who had been out door knocking.

Sen Abetz and fellow Liberal Senator Chris Back said the Liberals' policy for a $500,000 cap on superannuation contributions - backdated to 2007 - was a key reason some Liberal voters rejected them in the Senate.

Sen Back said some Liberal supporters had told him they would support the party in the lower House, but not in the Senate, because of the policy.