Istanbul (CNN) -- The government of key U.S. ally Turkey began to crack this week. There are rumblings that an Islamic cleric living in the United States may have something to do it.
But prosecutors in Istanbul have said corruption is the culprit.
Three Cabinet ministers resigned their posts Wednesday, days after their sons were arrested or temporarily detained in an anti-graft sting, semiofficial news agency Anadolu reported.
One of them -- Urbanization and Environment Minister Erdogan Bayraktar -- went further than the other two, not just resigning his Cabinet position but also calling on Prime Minister Recep Tayyip Erdogan to step down.
On live television in Turkey, Bayraktar said Erdogan asked him to resign and make a statement that would ease pressure on Erdogan. Upset at this, Bayraktar declined to make the statement but stepped down from his Parliament seat as well as his Cabinet post, and called on Erdogan to resign "to make the people more comfortable."
"They sent us two papers today -- one for our resignation, the other a statement. Of course I want to make it easier for my party. However, I find this wrong," said Bayraktar, whose son was briefly detained in the roundup but later released.
Economy Minister Zafer Caglayan and Interior Minister Muammer Guler, whose sons were also arrested in the probe, also resigned Wednesday. Erdogan accepted the resignations, Anadolu reported.
The sons were detained in a roundup that included the head of a public bank, several bureaucrats and high-profile businessmen. It came after a two-year probe by the Istanbul Prosecutor's Office into allegations of corruption including money laundering, gold smuggling and bribery.
Also, local media outlets reported that former interior minister Idris Naim Sahin resigned from Erdogan's ruling Justice and Development Party or AKP. Sahin, who served as interior minister before Guler, will retain his seat in Parliament.
The sweep comes in the runup to local elections in Turkey. Erdogan had been expected to reorganize his Cabinet, because some of his ministers will be running for office in March. Late Wednesday, he announced a Cabinet reshuffle, naming 10 new people.
"I had mentioned previously that there was the possibility of change by the end of the month. Some (ministers) asked to be removed. Some left their positions. Some are my decisions, which I submitted to the President and he has approved," Erdogan said.
Efkan Ala was tapped as interior minister, Idris Gulluce as urbanization and environment minister, and Nihat Zeybekci was announced as the nation's new economy minister.
One of Erdogan's old allies, now a rival, could be having an influence on the crackdown, which Erdogan has called a "dirty, dirty operation" aimed at toppling his government.
Erdogan appears to be in an open power struggle with former political backer Fethullah Gulen. Gulen is an Islamic cleric living in self-imposed exile in Pennsylvania, and his supporters are thought to be in key positions within the police force and the judiciary.
Top government officials accused Gulen recently of trying to establish a "parallel state" within the Turkish government.
The Hizmet Movement, the name preferred by Gulen's followers, has in the past thrown its support behind the Erdogan-led AKP. But the two have been publicly at odds over the last month.
"It was a forced marriage and now it's an ugly divorce," said Ahmet Sik, a journalist who wrote a book on Gulen and his influence within the judiciary and the police force.
In the wake of the arrests, Guler, who as interior minister controls the police force, dismissed scores of senior police officers. The government justified the purge by accusing them of carrying out the corruption arrests outside the chain of command.
Journalists were hindered from covering the mass firings.
Journalists accredited with the Turkish police were ordered to hand in their credentials as well as keys to the media briefing rooms in some police stations. "If there are any developments or press statements press members will be invited," read a statement from the police.
Reporters who had long worked the police beat said the ban was unprecedented.
According to press reports, Guler had no prior knowledge of the corruption probe that led to the detention of his son and the sons of the other ministers. He has denied any wrongdoing.
Erdogan has repeatedly claimed, since the corruption arrests began on Tuesday, that international organizations with branches inside Turkey are trying to destabilize the country.
"This country has never been and never will be the operational space of international organizations. We will not allow the interest lobby, the war lobby, the blood lobby to carry out an operation under the guise of a corruption operation," he said during a speech on Sunday.
CNN's Saad Abedine, Talia Kayali and Jason Hanna contributed to this report.