With the pending appointment of environmental spokesman Henri Bontenbal as the CDA’s new leader, the main party line-up for the autumn election campaign is complete.

Bontenbal’s appointment is set to be confirmed on Monday. The 40-year-old faces a difficult task to head off the challenge presented by the pro-farmers BBB in the CDA’s traditional farming heartland.

The party, part of the outgoing coalition, currently has 15 seats in the 150-seat parliament but opinion polls currently indicate that total could halve, if not more, at the November 22 vote.

Bontenbal is the fourth new leader for the four coalition parties – replacing foreign affairs minister Wopke Hoekstra who said soon after the cabinet collapse that he would not stand for re-election.

The VVD will fight the campaign with justice minister Dilan Yesilgöz replacing Mark Rutte, Rob Jetten, the climate minister, takes over from Sigrid Kaag and Mirjam Bikker will succeed Gert-Jan Segers at minor Christian party ChristenUnie.

The big newcomer outside the current coalition is former European commissioner Frans Timmermans, who will lead the combined PvdA GroenLinks campaign.

Caroline van der Plas, leader of the BBB, is currently the party’s sole MP but support for the pro-farming group has been soaring and she is set to pose a considerable challenge to the existing line-up.

Popular independent MP Pieter Omtzigt, who polls suggest would emerge as the big winner in November, has yet to say what his plans are.