The four parties in the right-wing coalition would win 67 seats if a general election were held now, leaving them nine short of a majority, according to a new opinion poll.

The panel survey for Maurice de Hond’s website shows a dramatic drop for Nieuw Sociaal Contract, who won 20 seats at the last election a year ago. Pieter Omtzigt’s party is projected to hold on to just three of its MPs.

Omtzigt, who returned to work last week after stepping back for two months on the advice of his doctor, told a party conference at the weekend that it was important to stay in the cabinet “so that all four of us can achieve our aims”.

Two NSC junior ministers and two MPs have quit in the last three weeks, citing concerns about the increasingly abrasive nature of public debate and the behaviour of PVV party leader Geert Wilders.

The PVV remains the most popular party in parliament, but despite NSC’s collapse, Wilders’s group would only gain only one seat more than the 37 it won a year ago.

The right-wing liberal party VVD, the second largest member of the coalition, would got from 24 seats to 19, while the farmers’ party BBB would keep its seven MPs.

CDA main winners

The big winners in the last 12 months are the centre-right Christian Democrats (CDA), who were reduced to a historic low of five seats last November.

The party’s fortunes have revived under Henri Bontenbal, who has positioned it as a moderate right-wing alternative to the coalition. Last November Bontenbal ruled out any kind of formal power-sharing arrangement with the PVV.

The main left-wing opposition group GroenLinks-PvdA has been unable to make any headway since the election, despite the internal rows and lack of progress by the ruling parties. They are projected to retain their 25 seats.

Several other parties on all sides of the political spectrum are expected to make smaller gains, including D66, up from nine seats to 11, far-right Forum voor Democratie (FVD), who have risen from three seats to five, and pro-European Volt, who would double their contingent of two MPs.