Buma, who has hopes of becoming the next Dutch leader, initially said he could not predict what he would do, but then said he would withdraw the ratification instrument.
His remarks followed the first national election radio debate on Radio 1 that took place on Friday (24 February), in which Buma said that other countries will follow the United Kingdom out of the EU unless the bloc “drastically” reformed.
“If Europe continues on the same track, Brexit will not be the end of it,” he said Buma.
Buma’s centre-right party is a member of the European People’s Party (EPP), the largest political force in the European Parliament, and traditionally very pro-EU.
But Buma appears to be wooing Dutch voters who are disillusioned with European integration and worried about migration, the two main constituencies of Dutch anti-EU populist Geert Wilders, who is leading in the polls.
Buma said on the radio that Europe needed to be less focused on “small bureaucratic rules”.
Earlier last week, in an interview with financial newspaper Financieel Dagblad, he also criticised EU rules on public tenders.
“It is impossible to explain if Europe means that you are not allowed to give your own companies some help,” he said.
The EPP politician’s eurocritical position has come under fire from Alexander Pechtold, a liberal and pro-EU Dutch MP who also has his sights set on the prime minister’s post.
Pechtold said Buma was “acting like the Party for Freedom” – referring to Wilders’ party – to win votes.
Islam: threat or enrichment?
Wilders and current prime minister, centre-right Mark Rutte, cancelled their appearances in Sunday’s tv debate, broadcast by RTL.
Like the other four debaters who did come on Sunday, Buma disagreed with the perception that Islam is a threat for Dutch identity.
“But I will not call it an enrichment,” said Buma, who listed Islam alongside health care as one of Dutch people’s “worries”.
He said that after four years of the pragmatic coalition between Rutte’s centre-right Liberals, and deputy prime minister Lodewijk Asscher’s centre-left Labour, the Netherlands is “more angry, more afraid, more divided than ever”.
Asscher also appeared to tack toward voters who were worried about immigration.
More or less refugees?
When asked if the Netherlands should accept more refugees, he said he disagreed.
“The Netherlands has already done a lot,” he said.
The leader of centrist pro-EU party D66, MP Alexander Pechtold, and his colleague from GreenLeft, MP Jesse Klaver, said the Netherlands should take in more people.
Both debates were mostly about domestic issues, such as the cost of health care, euthanasia, traffic congestion, and whether employers should be allowed to fire people more easily.
US president Donald Trump was mentioned, as well as Nato.
GreenLeft leader Klaver was asked whether as prime minister he would apologise to Trump for calling him a «mafklapper» (an untranslatable, but relatively friendly insult). Pechtold said he would show Trump around, joking he would bring him to two Dutch amusement parks.
Christian-Democrat Buma said his party would increase defence spending to reach the EU average, but not the 2 percent of GDP that Nato members had promised each other in 2014.
At Friday’s radio debate, which had prime minister Rutte present, Rutte said the 2 percent goal should be reached “in the long run”, but he would not name a year.
The latest polls show Wilders’ party in the lead, set for 24-28 seats of 150, closely followed by Rutte’s party at 23-27 seats.
The runners-up are CDA, D66, and GreenLeft, each between 15 and 19 seats.