Opposition parties have given a lukewarm response to a proposed deal by the coalition to break the deadlock over its education budget.

Five opposition groups – D66, CDA, J21, the ChristenUnie and the orthodox Protestant SGP – have threatened to block the budget in the Senate unless the government scraps or waters down most of its €2 billion cuts package.

Dutch media reported that the right-wing coalition had offered to reverse €363 million worth of proposed savings during talks behind closed doors on Monday. The offer is far less than the €1.3 billion that the opposition alliance has demanded.

Both sides said the discussions in the office of Geert Wilders, leader of the far-right PVV, the largest party in the coalition, had been constructiv. But one source dismissed the counter-offer as “blanks”, because the coalition did not say where the money would be taken from, NRC reported.

“We’re going to take our time to decide whether this is a serious offer,” Rob Jetten, leader of the progressive liberal D66 said, while Christian Democrat (CDA) leader Henri Bontenbal said the “puzzel has not got any easier”.

Bontenbal was reacting to leaked documents from civil servants that warned the coalition that schools could “have problems” if its plans to cut teachers’ salaries went ahead.

Doubts were also raised about the extra fees for students who take too long to finish their degree, which officials said could penalise people who were forced to suspend their studies because of illness or to care for a relative.

The opposition parties also want to retain the social inclusion programme known as maatschappelijke diensttijd for disadvantaged young people and abolish cuts to religious education.

They have called for the excess charge in health insurance to be cut by a smaller amount than 50% to compensate for the smaller cuts, but Wilders has called the measure a red line.

Prime minister Dick Schoof last week urged the nine parties to come up with a “total package” to settle their difference over the budget in one go. “We cannot have the same discussion week in, week out,” he said in his weekly interview with NOS.

Opposition parties have already forced a climbdown on plans to raise VAT on culture, books, newspapers and sport.