People wave Turkish flags as they gather in Taksim Square in Istanbul, protesting against the attempted coup, early Tuesday. (Emrah Gurel/AP)

Turkey suspended more than 15,000 education workers on Tuesday and demanded resignations from all university deans in an escalation of a far-reaching purge of state institutions following a failed coup attempt.

Turkish officials also said steps to curb the powers of the military are being considered, while President Recep Tayyip Erdogan said an “important decision” would be announced after national security leaders convene on Wednesday, raising expectations that more will follow.

More than 45,000 military officials, police officers, judges, governors and civil servants have also been fired, detained or suspended since a mutinous faction of Turkey’s military staged an attempted overthrow of the government Friday night, hijacking fighter jets and helicopters to strike key installations and security forces.

Critics say the escalating purge of state institutions is aimed at crushing all opposition and consolidating power in the hands of the president.

Mevlut Cavusoglu, Turkey’s minister of foreign affairs, said in an interview that the issue of civilian oversight of the military — a matter of long-standing debate within Turkish politics — would be addressed during Wednesday’s national security meetings. A government official, who spoke on the condition of anonymity because the announcement has yet to be made public, also said military reforms could be proposed.

The military has long seen itself as the guardian of secularism in this mostly Muslim country and has staged a series of coups in past decades, but its power has been gradually diminished. Thousands of Turks took to the streets to prevent another coup, but the crackdown has raised fears that Erdogan — who described the plot as a “gift from God” — will use it as an opportunity to make the government more authoritarian.

“The counter-coup is not over yet,” said Soner Cagaptay, a Turkey expert at the Washington Institute for Near East Policy. He said he believes that Erdogan is using the coup attempt as a “one-time window” to consolidate power and lead Turkey toward being a single-party state.

Erdogan is on track to “be the most powerful person in Turkey since the Ottoman Empire,” ­Cagaptay said.

The government official said military reform would likely bring the army chief of staff under the Defense Ministry and give parliament more oversight of the military’s budget and ranks.

In order to change the constitution without a referendum, Erdogan’s party will need support from 367 members in Turkey’s 550-seat parliament, Cavusoglu said. It needs 330 votes to hold a referendum.

Aaron Stein, a Turkey scholar at the Washington-based Atlantic Council, said there’s nothing intrinsically wrong with more civilian control over the military. “It depends on what model they use and how it gets drafted,” he said.

What we know about the failed coup attempt in Turkey

The United States and Europe have urged Turkey, a NATO member and ally, to follow the rule of law and maintain democratic principles amid the sweeping fallout from the coup attempt.

In a telephone call to Erdogan on Tuesday, his first to the Turkish president since the coup attempt, President Obama “strongly condemned” the insurrection and “lauded the Turkish people’s resolve against this violent intervention and their commitment to democracy.” A White House statement said Obama urged that investigations into the perpetrators “be conducted in ways that reinforce public confidence in democratic institutions and the rule of law” and said the United States would help the inquiry if asked.

Thousands of soldiers have been detained since the coup attempt, and senior military leaders have been jailed pending trial. The Turkish government has blamed the attempted overthrow on Fethullah Gulen, a cleric living in self-imposed exile in Pennsylvania who has links to education networks in Turkey and the United States, framing the widespread sackings as an effort to cleanse state institutions of his followers.

All university deans — a total of 1,577 — were asked to hand in their resignations Tuesday. A further 492 staff members at the country’s top Islamic authority were removed from duty, and 257 members of the prime minister’s office staff were sacked.

“We are shocked and perplexed,” said one university professor, who spoke on the condition of anonymity because he feared that any criticism of government decisions could be used against him. He said he thought that resignations would be accepted only from the deans who are thought to be followers of Gulen.

Last year, a Turkish court overturned an order to close Gulen-linked schools in the country. But since the coup attempt, Turkey has also sacked 2,745 judges. Nearly 9,000 members of the Interior Ministry have been suspended, while thousands more police officers and soldiers have been fired.

While rights organizations have complained that the dismissals and detentions appear to have been carried out with little investigation, Turkish officials contend that there has been a long-standing investigation into Gulen’s movement.

Prime Minister Binali Yildirim said Tuesday that Turkey aims to remove the movement “by its roots.”

Yildirim said that Turkey had formally requested Gulen’s extradition and that his role in the events of last week was “clear.”

“However, we will provide them with a pile of evidence,” he added, according to the state-run Anadolu news agency.

The White House statement did not comment on implications by Erdogan and others that the United States may be at least partly responsible for the uprising because of its refusal to extradite Gulen. Secretary of State John F. Kerry said this week that Turkey has made only “allegations” and that it has not provided evidence of what it says are Gulen’s past crimes or officially requested extradition.

White House press secretary Josh Earnest said that Obama and Erdogan discussed Gulen and that early Tuesday morning, “there were materials presented by the Turkish government in an electronic form to the U.S. government related to Mr. Gulen’s status.”

Earnest said that it wasn’t clear whether the materials constituted a formal extradition request but that they would be reviewed by the Justice and State departments consistent with the 30-year-old extradition treaty between the two countries.

“But the president also made clear a couple of other things,” Earnest said. “The first is that the United States doesn’t support terrorists, the United States doesn’t support individuals who conspired to overthrow democratically elected governments. The United States follows the rule of law.”

Extradition decisions, he said, are not made by the president but through a legal process and the courts.

Any disagreement over an extradition has the potential to put the United States on a diplomatic collision course with Turkey, which is a critical partner in efforts to defeat the Islamic State.

Erdogan has already publicly appealed to Obama to extradite Gulen, whom he accuses of running a terrorist organization.

Gulen has denied the claims that he was involved in the coup, implying instead that Erdogan staged it as part of a power grab.

The Pentagon said that Defense Secretary Ashton B. Carter spoke by telephone with his Turkish counterpart, Fikri Isik. Carter “reiterated the support of the United States for Turkey’s democratically elected civilian government and the rule of law,” and the two discussed “the importance of operations at Incirlik Air Base to the counter-ISIL campaign,” a statement said.

Both Isik and Cavusoglu canceled plans this week to attend a Washington meeting of the U.S.-led coalition against the Islamic State.

Earlier Tuesday, the Turkish military said it had received intelligence that a rogue element was embarking on a coup hours before hijacked tanks were deployed to the streets and rebel-piloted F-16s bombed key buildings in Ankara, the capital. The timetable raised questions about why quicker action was not taken to interrupt the plot.

The military said in a statement that it was given information on the coup plot by the National Intelligence Organization at 4 p.m. local time and informed relevant authorities. That was several hours before bridges in Istanbul were blocked in one of the first public signs that the action was underway.

After the intelligence was received, orders were given for all military aircraft to be grounded and for vehicles — particularly tanks and armored vehicles — to be prevented from leaving an armored unit training school in Etimesgut in a western district of Ankara, it said.

Still, several hijacked F-16s still managed to take off at around 10 p.m. that evening, bombing the parliament building and police bases. Rebel pilots of two F-16s also “harassed” Erdogan’s plane as he flew back from the coastal resort of Marmaris to Istanbul as the coup attempt was underway, according to the Reuters news agency.

Their radars locked onto the presidential plane but the pilots did not fire, the news agency said, citing a former military officer.

Zeynep Karatas in Istanbul, Carol Morello in London and Karen DeYoung and Brian Murphy in Washington contributed to this report.