Diederik Boomsma has become the latest MP to defect from NSC, the party founded by Pieter Omtzigt, after switching to anti-immigration party JA21.

Boomsma, 47, launched a failed bid for the leadership of NSC last month after Omtzigt quit and his successor, Nicolien van Vroonhoven, stepped down after the collapse of the four-party coalition, which included NSC.

He withdrew his candidacy after being criticised by Van Vroonhoven for advocating a tougher line on asylum and amending international treaties to give the Netherlands more control of its own borders.

Boomsma, previously NSC’s asylum spokesman, said JA21, which broke away from the far-right Forum voor Democratie five years ago and currently has one MP, was closer to the “new social conservative line” that he wanted NSC to take.

“NSC has good elements, but it has had little to show for it,” he told the Telegraaf on Friday.

Boomsma is the second NSC MP to switch party since the collapse of the government, following the defection of pension spokeswoman Agnes Joseph to the farmers’ party BBB, but unlike Joseph, Boomsma has chosen not to retain his seat.

NSC leader Eddy van Hijum said he was disappointed by his former colleague’s decision, but added: “I have to acknowledge that he has found a different home. I have to respect that. I respect the fact that he is not taking his seat with him.”

Another NSC MP, Aant Jelle Soepboer, quit parliament three weeks ago to become leader of the Frisian National Party (FNP).

Coenradie boost

NSC will continue with 19 MPs, although opinion polls indicate it could be wiped out in the election on October 29, while JA21 is represented by Joost Eerdmans.

Boomsma is the second high-profile acquisition by JA21 after Ingrid Coenradie, who represented the PVV as junior justice minister in Dick Schoof’s cabinet, switched allegiance when the government fell.

Coenradie’s arrival coincided with a spike in support for JA21, which is currently projected to win between five and nine seats in October.

Eerdmans called Boomsma “a talented MP who has a detailed understanding of political handiwork and will make a difference for everyone in the Netherlands who is crying out for curbs on migratiton, a smaller, effective government and a stronger economy where work is rewarded again.”