AMSTERDAM (Reuters) - The Netherlands faces political disarray after the March 15 election as mainstream parties, diminished by losses of voters to nationalist leader Geert Wilders but refusing to work with him, struggle to forge a viable coalition.

Dutch Campaign posters are seen in front of a windmill in Amsterdam, the Netherlands, March 1 2017. REUTERS/Michael Kooren

Wilders, the anti-Islam, anti-EU firebrand running almost neck-and-neck with conservative Prime Minister Mark Rutte, stands to double his seat total in parliament while the two coalition parties’ share is cut almost in half.

The political landscape is fragmenting after decades of stable consensus. Seven major parties will jostle for power and toil to find common ground on hot-button issues such as Muslim immigration, national identity and elderly care that have polarized the European Union nation of 17 million people.

The emerging prospect that the biggest party may not command more than some 25 seats in the 150-strong parliament, with Wilders and a slew of fringe parties hiving off votes from the center, will complicate the building of a durable coalition.

“The Netherlands has always had a lot of smaller parties. But what is new here is that the so-called ‘big’ parties have become so small,” Radboud University political scientist Kristof Jacobs said.

The tried-and-true Dutch model of consensual stability could fray if no party secures a clear mandate to lead - a trend seen in other EU countries as eurosceptic populist movements have scooped up voters disenchanted by “establishment” parties.

The Netherlands may be heading for a period of political dysfunction similar to that seen in neighboring Belgium, where it took four parties five months to assemble a coalition in 2014 - an improvement on the 541-day formation talks of 2010-2011.

Wilders’ Party for Freedom (PVV) had led pre-election polls since November before slowing slightly to second place by Monday with nearly 15 percent of the vote, just one percent behind Rutte’s conservative VVD party.

With the two frontrunning parties in a virtual dead heat, Rutte said Wilders could still pull off a victory.

“We are now number one in the polls, but we still have the Freedom Party just behind us,” Rutte said. “So there is still a big risk that he could come out number one.”

Tradition in the Netherlands, one of the EU’s founding member states and among its most prosperous, holds that the party that gets the most votes oversees coalition talks.

But even if Wilders ekes out victory, extending the popular backlash against globalisation after Britain’s vote to leave the EU and Donald Trump’s election as U.S. president, he is more likely to end up back in opposition since all Dutch mainstream parties have vowed to ostracize him, analysts say.

DESTABILISING POST-ELECTION SCRAMBLE

A future Wilders-free coalition may need to accommodate up to a half dozen mainstream parties. This could make for shaky alliances involving pro-business conservatives; centre-right Christians; centrist liberals; center-left Labor, now the junior governing party; or left-wing Socialists or Greens.

“It’s maybe predictable who gets what number of seats, but not what coalition the Netherlands will end up with,” said Nienke Bos, a political scientist at Leiden University.

Anxious to dent Wilders’ appeal, all main parties now call for cuts to immigration, especially of economic migrants.

But they are at odds over social policy in an era of budget restraint, including the retirement age, how much should be spent on caring for swelling numbers of elderly people, and whether patients should make a starting contribution to medical treatments on top of mandatory health insurance payments.

“Whatever happens, we can brace for long coalition talks: historically we see them getting longer compared with the 1980s and 1990s,” Bos said. “All parties will try to keep their options open.”

Finance Minister Jeroen Dijsselbloem said that a caretaker government could run the Netherlands for up to four years during marathon coalition negotiations.

“That could happen if the talks in The Hague are fruitless, but we have a tradition in the Netherlands of forming coalitions even with so many parties (in play),” he said.

Rutte’s party has adopted much of Wilders’ tough line on immigration to try to stop the erosion of its voting base since winning the 2012 election. But he says the chance of the conservatives entering a coalition with nationalists is “zero”.

When Wilders suggested that such pledges would be discarded if the PVV wins on March 15, Rutte posted a categorical answer on his Facebook page: “It. Will. Not. Happen.”

Sybrand Buma, leader of the centre-right Christian Democratic Appeal (CDA), regarded as a strong contender to be in the next coalition, repeated his refusal to deal with Wilders during a live television debate last week. “Oh, come on!” Buma said when asked if he would reconsider.

POPULIST “REVOLT”?

Wilders initially forecast “revolt” among his followers if he won the popular vote only to be locked out of government. He declined to elaborate and later backpedalled, stating his “intention is for this revolt not to happen”.

“If voters make us a strong party it will be difficult to ignore us, though they (mainstream parties) will try,” Wilders told journalists on Sunday. If the PVV were indeed kept out of government, he added, “we will be the toughest opposition party the Netherlands has ever seen”.

For many centrist politicians, his conflicting remarks about “revolt” strengthened their resolve not to negotiate with the combative populist.

Wilders’ calls to ban Muslim immigration, mosques and the Koran and take the Netherlands out of the EU have drawn many voters who have soured on open borders and multiculturalism, seeing them as threats to national identity.

But he gained a reputation for unreliability among other parties after triggering the collapse of a minority government in 2012. “Most parties do not seem inclined to risk repeating that experience” by teaming up with Wilders, said Bos.

“The chances of a government that includes Wilders are very slim,” said Hans Goslinga, political commentator for the Christian newspaper Trouw. He predicted a centrist coalition, though possibly a minority one, between the conservatives, Christian Democrats and the liberal Democrats 66.

Analysts said one path to power for Wilders could open up if the CDA and VVD were decisively beaten by the PVV on March 15 and Rutte and Buma felt bound to step down. This could yield a right-wing bloc taking in the PVV, VVD and the 50Plus pensioners party. Like Wilders, 50Plus aims to lower the retirement age to 65. Rutte raised it to 67 in an unpopular austerity move.

In any post-election scenario, analysts see scant chance of a “Nexit” advocated by Wilders, since consistent majorities of the Dutch people and parliament are opposed to leaving the EU.

Still, with more than half of eligible voters still undecided in the latest polls, any political forecast in the Netherlands this time must be taken with a grain of salt.

“With 28 parties to choose from it will be hard to cast a vote,” undecided voter Stefan Steur said in the town of Volendam. “Then it will be even harder to form a coalition with all those small parties that get just a few seats each.”