Geert Wilders, the maverick Dutch anti-Islam campaigner, has emerged triumphant as the linchpin of a new rightwing minority government pledged to banning the burqa in the Netherlands, cracking down on immigration, strengthening the police and slashing public spending.

Almost 16 weeks after a general election in which Wilders' Freedom party almost tripled its vote but from which there was no clear winner, Liberals and Christian Democrats in the the Netherlands agreed a minority coalition pact supported in parliament in The Hague by Wilders's 24 seats.

The deal could still come unstuck this weekend, with many Christian Democrats uneasy about forming a coalition a man who goes on trial on Monday in Amsterdam on charges of hate speech and inciting racism.

The Christian Democrats are to hold a party congress tomorrow to bless or reject the coalition pact. Analysts expect a green light from the congress for what will be a fragile government, the most rightwing in the Netherlands in decades.

An opinion poll yesterday showed majority Dutch support for the new government.

The 46-page pact drawn up by the Liberal and Christian Democrat leaders puts Wilders in the strong position of exercising power without responsibility. His party will not be in the government but will support the coalition in parliament in return for crucial policy concessions.

"A new wind will blow in the Netherlands," he said. "We have enormous influence … It's a beautiful day for the Netherlands."

The leaders of the new government – Mark Rutte, head of the Liberal VVD party and the new prime minister, and Maxime Verhagen, leader of the Christian Democrats and current foreign minister – were more muted in marking the breakthrough. Between them the two parties muster a mere 52 seats in the 150-seat second chamber or lower house in The Hague. With Wilders's caucus voting with the government it has a wafer-thin majority at 76 seats.

Wilders has won pledges to introduce legislation banning Islamic headgear, joining France, Belgium and Switzerland in a growing campaign across Europe to ban a veil that relatively few Muslim women wear.

The coalition will aim to halve immigration, emulate Denmark in making it difficult for the spouses and children of immigrants to join them, and deport immigrants found guilty of crimes meriting sentences of 12 years.

It is committed to slashing public spending by €18bn and will take a more Eurosceptic position towards Brussels, fighting for lower contributions to the EU budget.

The inauguration of the new government next week looks likely to coincide with Wilders's trial, which opens in Amsterdam on Monday.

Wilders was once banned from entering Britain by Gordon Brown's government. He is going to Berlin tomorrow to drum up support for a pan-European anti-Islam movement of the far right.