Political expert Nick Economou said a decision by the Electoral Commission to modify the boundaries of 22 of the electoral divisions would make it much easier for Mr Tehan to retain Wannon.

But Dr Economou, a Monash University politics lecturer, said the move would make it harder for Corangamite MP Sarah Henderson to keep her already marginal seat.

“The flip side is the excision of Colac from Corangamite will make it very marginal,” he said.

“Tehan has nothing to worry about. What he does have to worry about is if the Liberal Party lose the election and would he still be in the Shadow Ministry. There’s no doubt he’s a player in the Liberal leadership.

“Henderson, though, has a real fight on her hands.”

The changes mean Wannon will expand to take in Colac, (currently part of the Corangamite electorate), Smythesdale (Ballarat) and Stawell (Mallee).

Electoral Commissioner Tom Rogers said all written objections and comments, as well as the information presented at the inquiries had been carefully considered in deciding the final boundaries.

The Commissioner also agreed to retaining the name of Corangamite after it was proposed the electorate be renamed Cox.

Corangamite MP Sarah Henderson said she was incredibly disappointed to have lost large parts of the electorate, including Colac and district and parts of the Golden Plains. “It has been an honour to represent these communities,” she said. “With Colac and district moving into the Wannon electorate, these communities will be very well served by the hard-working Dan Tehan. I am extremely pleased that the indigenous name of our federation seat will be maintained, reflecting the importance of our history and indigenous heritage.”

The boundaries changes will apply from July 13.