An unexpected twist in the run-up to next year’s Indonesian presidential election puts  Centrist Democratic International (CDI), the world’s largest alliance of conservative political parties, and Nahdlatul Ulama, the world’s largest and most moderate Muslim civil society movement, in a bind.

In a surprise move, Muhaimin Iskander, leader of the National Awakening Party (PKB), founded in 1998 by five Nahdlatul Ulama clerics, including the movement’s one-time leader and former Indonesian president Abdulrahman Wahid, joined Anies Baswedan, as his vice-presidential candidate.

A US-educated political scientist and former Jakarta governor with close ties to conservative Muslim circles and a penchant for identity politics, Mr. Anies is supported in next February’s election by the Prosperous Justice Party (PKS), the PKB’s arch-rival widely believed to be affiliated with the Muslim Brotherhood.

“This is concerning,” said a senior CDI official.

Even so, and despite the bad optics of Mr. Muhaimin’s move, neither CDI, of which PKB is a member, nor Nahdlatul Ulama, with 90 million followers, is likely to respond forcefully unless Mr. Anies reverts to identity politics.

Nahdlatul Ulama quickly denied a PKB assertion that the movement backed Mr. Muhaimin’s move. Nahdlatul Ulama emphasised that it was not endorsing any presidential candidate.

“There should not be any contenders that (present themselves) on behalf of the NU. If there are any, they are doing it on their own capacity and track record,” said Nahdlatul Ulama chairman Yahya Cholil Staquf.

Mr. Staquf’s relationship with Mr. Muhaimin has long been strained.

Mr. Anies’ choice of Mr. Muhaimin appears to be a ploy to win votes in Nahdlatul Ulama’s Javan strongholds. The move underscores the movement’s political influence.

Like Indonesian President Joko Widodo, the country’s most popular politician, Nahdlatul Ulama is positioned to play an influential backroom role.

For now, Mr. Anies is trailing in opinion polls behind the two other leading presidential candidates, Defence Minister Prabowo Subianto and Central Java Governor Ganjar Pranowo.

Messrs. Prabowo and Ganjar expect to nominate their running mates in the coming weeks. Mr. Muhaimin hoped he would be Mr. Prabowo’s nominee.

However, the presidential candidate appears to lean towards either Gibran Rakabuming, President Joko Widodo’s eldest son; Yenny Wahid, a daughter of the former Nahdlatul Ulama leader; or State-owned Enterprises Minister Erick Thohir, a businessman and member of the five-million-strong Nahdlatul Ulama militia.

Mr. Prabowo met Ms. Wahid earlier this week.

To appoint Mr. Gibran, the Constitutional Court would have to lower the age of presidential and vice-presidential nominees to 35, an issue the court is debating.

While Mr. Muhaimin’s association with a Muslim Brotherhood affiliate would be sufficient to suspend PKB’s CDI membership, CDI will likely monitor developments at this point.

Analysts suggest Mr. Muhaimin’s move could either disrupt the coalition backing Mr. Anies or end Mr. Muhaimin’s political career and PKB leadership if his vice-presidential bid fails.

“It’s a long-term game,” said one analyst.

Past attempts to unseat Mr. Muhaimin have failed.

Mr. Anies’s partnership with Mr. Muhaimin has prompted the Democratic Party to withdraw from the presidential candidate’s three-party Coalition of Change for Unity (KPP).

The Democratic Party expected Mr. Anies to nominate Agus Yudhoyono, the party’s chairperson and the eldest son of former president Susilo Bambang Yudhoyono, as his running mate.

For its part, the PKS said its religious advisory board would need to approve Mr. Anies’s choice of Mr. Muhaimin. Analysts noted that the PKS was absent when Messrs. Anies and Muhaimin announced their partnership.

The PKS attacked Mr. Staquf in 2018 for visiting Israel at the invitation of the American Jewish Committee.

A former PKS head and parliament speaker, Hidayat Nur Wahid, refused in 2020 to join a Saudi-led groundbreaking to Auschwitz, the Nazi death camp in Poland.

Mr. Hidayat has long-standing ties to the Muslim World League, a Saudi government-controlled non-governmental organisation that, before Crown Prince Mohammed bin Salman’s rise in 2015, was populated by Muslim Brotherhood figures.

For Nahdlatul Ulama and CDI, the optics are complicated given that the PKB nominally has four ministers in President Widodo’s cabinet, including Religious Affairs Minister Yaqut Cholil Qoumas, an influential Nahdlatul Ulama figure who heads the movement’s militia and Mr. Staquf’s younger brother.

In addition, Mr. Muhaimin is one of 16 vice presidents of CDI, which groups 109 right-wing parties in 83 countries.

Like Nahdlatul Ulama, CDI is virulently opposed to the Brotherhood and political Islam.

Driven by Mr. Staquf, Nahdlatul Ulama has embraced a concept of Humanitarian Islam that propagates religious as well as political pluralism and unambiguous endorsement of the Universal Declaration of Human Rights.

The movement advocates reform of religious jurisprudence that removes from Sharia outdated, obsolete, and discriminatory tenets, such as the notion of a kafir or infidel, and replace the concept of a caliphate with that of a nation-state.

Analysts suggested the optics projected an oversimplified view of a complex game, part chess and part poker.

“This will play out over time. Where this leads to may only be clear after the election,” the analyst said.