A sitting Victorian Liberal MP is being challenged for preselection by a pro-life campaigner who believes women should never have abortions, even in cases of rape.

Stephanie Ross – the partner of "Young Turk" and party numbers man Marcus Bastiaan – is preparing to challenge 65-year-old incumbent Gary Blackwood for his Gippsland seat of Narracan.

Preselection candidate Stephanie Ross, Brighton Liberal James Newbury, and party numbers man Marcus Bastiaan. Credit:Twitter

The looming preselection stoush has heightened concerns about a push to drag the Liberals further to the right, which many fear could hinder their chances of defeating Labor at the 2018 Victorian election.

Ms Ross, 25, is aligned with the Menzies branch of the party, which is controlled by conservative warrior and former defence minister Kevin Andrews.