In mid-February, Muhammad al-Khaththath, leader of the hard-line Muslim Community Forum, held court on the top floor of a Jakarta fast-food joint. With key deputies gathered around, he explained the direction he hoped to push relatively secular, democratic Indonesia.

Sharia would become the law of the land, non-Muslims would lose their leadership posts, and thieves, in accordance with Islamic law, would have their hands lopped off, he said. He also criticized Joko Widodo, Indonesia's pluralist president.

Widodo "isn't a liberal Muslim," Khaththath said. "He's a Muslim who doesn't get it."

Six weeks later, Khaththath was detained on treason charges, accused of plotting a coup. But in an April 19 runoff election for governor of Jakarta, his preferred candidate, fellow Muslim Anies Baswedan, defeated the Christian incumbent, Basuki Tjahaja Purnama, after a campaign laden with religious overtones.

Since then, hard-line Islamist groups have gained stature; their ability to mobilize huge crowds was considered crucial to securing Baswedan's lopsided victory. But a strong backlash also has emerged, led by moderate Muslims who worry that conservative Islamists are wrecking Indonesia's tradition of religious tolerance.

Khaththath had taken over as the leader of a powerful protest movement against Purnama, a Widodo ally, in the months leading up to the gubernatorial election, after the previous leader was summoned by police on pornography charges.

But police came for Khaththath in late March, escorting him from his hotel room to the detention facility where he remains. A few weeks later, on the eve of the election, Khaththath managed to send out a letter to his supporters. "From my detention room, I tap on the sky door," Khaththath wrote. He hoped the tap would be felt by "every Muslim heart" and would persuade the faithful to "choose a Muslim governor."

Not every Muslim heart felt the tap, but enough did to secure a clean victory for Baswedan. The high-stakes election campaign was marked by the largest conservative Islamist rallies in generations, as well as by intensifying - and controversial - legal efforts by the Indonesian government to rein in the hard-line groups' leadership.

Now that the election is over, many moderate Muslim leaders say they are treating it as a wake-up call about the growing power of Indonesian hard-line organizations and the need to take stern action to stop them.

"I am not worried about the candidates who won," said Sidarto Danusobroto, a former speaker of the Senate and key adviser to the president. "I am worried about the groups that supported them - the Islamic Defenders Front and Hizbut Tahrir."

"Islam is different from how the Islamic Defenders Front portrays it," said Mohammad Nuruzzaman, head of strategic research for Ansor, a moderate Muslim youth movement that has been working with the police to break up hard-line Muslim gatherings.

In one of a number of efforts in the past few weeks to curb extremists, police officials and nationalist groups in the central Javanese town of Semarang prevented the Islamic Defenders Front from opening a branch.

"We have a tolerant city," explained Iwan Santoso, a representative from the Red and White, a group that takes its name from the colors of the Indonesian flag. "We don't want students to be instigated."

This week, police in East Java, apparently acting at the urging of moderate Muslims or nationalists, shut down a planned university event featuring Felix Siauw, a Chinese Indonesian convert to Islam who has become a major hard-line preacher. In a Web video subsequently uploaded to his Facebook page, Siauw complained, "We should have a nation of laws, and the laws should apply to all."

But moderate Muslim and civil society groups increasingly are calling for bans on Muslim organizations that push for the creation of a caliphate. Nuruzzaman compared such organizations to the Indonesian Communist Party, a boogeyman from Indonesia's past.

"The goal of Communists and those who support the caliphate are similar - both want all countries in the world to be run under one system," he said.

On Tuesday, police announced that they were reviewing the legality of Hizbut Tahrir because of the international Islamist group's embrace of a global caliphate. Muhammad Ismael Yusanto, a spokesman for Hizbut Tahrir here, protested that its goal of establishing a caliphate does not violate the Indonesian constitution.

"All we do is convey Islam's teachings," he said in an interview. Besides, he argued, the constitution can be amended.

Hizbut Tahrir is banned in many countries around the world, including Germany, China, Egypt and numerous other Arab states. But it has operated for nearly 20 years in democratic Indonesia.

Some rights activists oppose banning the group. Andreas Harsono, Indonesia representative of Human Rights Watch, said that although Hizbut Tahrir's ideology is deeply discriminatory - toward women, LGBT people and minority faiths - that does not mean the organization should be shut down.

"It is not illegal to say 'I want to discriminate against women,'" he argued, acknowledging that the case is "complicated."

More worrying to Harsono are the Indonesian government's efforts to pursue radical religious leaders for alleged offenses unrelated to their Islamist activism, or on exaggerated charges. Habib Rizieq, perhaps the nation's most powerful hard-line figure, was brought in for questioning by police over pornographic images he allegedly exchanged with a woman not his wife, while Khaththath, the detained Islamic leader, was charged with trying to organize a coup.

"It's very concerning," said Harsono, who said he knows of no evidence that Khaththath was plotting the violent overthrow of the government.

Marcus Mietzner, an associate professor at Australian National University, expressed worry that heavy-handed charges would harm Indonesia's democracy.

"What they should not do is arbitrarily throw criminal charges at individual leaders that are either excessive, like the treason accusation, or unrelated, as the pornography case," he wrote in an email. "This, in turn, will only increase the sense of victimization among conservative Muslims."

That already appears to be happening. Achmad Sofyan, a Khaththath deputy who was also investigated by police, said: "It isn't fair. The case was engineered."

Mietzner suggested that the government has legal ways to handle hard-line groups but has opted for different tactics in part to avoid a messy public debate. If the state prosecuted these groups, "it would have to argue in front of the courts why Islam should not be Indonesia's primary legal-political foundation," he wrote.

For Nuruzzaman, the moderate Muslim leader, it is crucial to oppose the hard-liners, whatever the difficulties. "We don't want the government to take repressive measures," he said. Nonetheless, "we have to confront them."