"It is very likely that far fewer men will take paternity leave if the proposal is implemented. It would most likely lead to more unequal division of labour in the home," said Andreas Kotsadam, a post-doctoral researcher.
New research undertaken by Kotsadam, based on extensive interviews of 17-year-olds, showed that boys born after the introduction of the quota in 1993 did much more housework than those born previously.
"Our interviews show that children born just after paternity leave scheme was introduced had a much more even distribution of housework than other children," he told the Vårt Land newspaper.
Conservative spokesperson Erna Solberg dismissed Kotsadam's argument, saying that he underestimated how entrenched paternity leave, or 'pappapermisjon' had become in Norway.
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"I think that 19 years of paternity leave has changed society and that Norway is now ripe for an optional scheme," she said. "I think men will take paternity leave even after we make the scheme optional."
Both the Conservatives and their allies the Progress Party have said they will scrap the use-it-or-lose-it quota if they win the general election this autumn.