Former finance minister and ABN Amro chief Gerrit Zalm is taking over the role of chief negotiator in the ongoing efforts to form a new Dutch coalition government, sources have told the Telegraaf.

Four parties – the Liberals (VVD), Christian Democrats (CDA), D66 and the Christian Union (CU) – will sit round the negotiating table on Wednesday to start working out the details. The CU was previously rejected as a coalition partner by D66 because of their strong differences on ethical issues such as euthanasia.

Tjeenk Willink is due to report to parliament on Tuesday on his efforts to put together a coalition following the election on March 15, which saw 13 parties elected to parliament. If the four parties do a deal they will have a majority of just two in the lower house and one in the senate.

NOS said the 75-year-old Tjeenk Willink felt his job was done after whittling down the possible coalition options to one. The CU was invited back to the table after attempts to form a coalition with the green party GroenLinks broke down over the issue of immigration and asylum.

Caretaker prime minister Mark Rutte said he was ‘looking forward to the talks’ after the four party leaders went out to dinner together last week. Rutte’s VVD party is said to favour Zalm as Tjeenk Willink’s replacement for the detailed negotiations.

The remaining nine party leaders have been invited to discuss the outcome of the preliminary talks with Tjeenk Willink before he concludes his report. PVV leader Geert Wilders has declined the invitation.

Wilders clashed with the senator during the formation of the government in 2010, accusing him of lacking impartiality and favouring a coalition that would have excluded his party. In the end Rutte formed a minority government with the CDA supported by PVV votes, which lasted less than 18 months.