Without a doubt, 2013 will be a year Turkey’s powerful leader, Recep Tayyip Erdogan, will do his best to forget.

Prior to this year, Erdogan – in power since late 2002 – had gotten used to seeing things go his way. Rivals, in the form of the military and the old secularist establishment, had been vanquished. Plaudits for Turkey’s foreign policy and economic growth were coming in on a regular basis. And, following a third straight victory at the polls in 2011, Erdogan was being hailed as one of the political giants of the modern Turkish Republic, perhaps even an invincible one.

Things have worked out a bit differently in 2013. On the foreign policy front, Turkey found itself increasingly isolated in the Middle East this past year, as its aggressive policies regarding Syria, Egypt and Iraq, accompanied by ever tougher talk from Erdogan, failed to deliver tangible results (of the positive kind, that is). On the domestic front, the summer’s Gezi Park protests and Ankara’s heavy-handed response to them presented the most serious homegrown challenge Erdogan had yet to face, while his insistence that the protests were somehow part of a shadowy international conspiracy to topple him seriously tarnished his reputation abroad. Meanwhile, the PM’s effort to have a new constitution passed this year that would provide for a more powerful office of the president that he would assume failed, leaving Erdogan with a less clear path forward (the bylaws of his Justice and Development Party (AKP) forbid him from serving more than three consecutive terms as PM).

Things got much worse this past week, though, with the detainment on corruption charges of the sons of four AKP ministers, an AKP municipal mayor from Istanbul and several businessman with close ties to Erdogan. Smart money puts the hand of the powerful Gulen movement – which has deep judicial and police ties and which has gone from being an ally of Erdogan to growing increasingly disenchanted with his policies and autocratic style – as being behind the arrests.

The arrests come only weeks after Erdogan declared that his government plans to shut down Turkey’s system of university entrance exam preparatory schools, which are known to be heavily dominated by the Gulen movement, providing it with both a source of revenue and, as some suspect, recruits. The vehemence with which Gulen affiliated organizations and media reacted to the prep school closure move – which was ultimately delayed – certainly indicated that they had a lot at stake in the matter.

The actions taken by the police and prosecutors this past week, meanwhile, felt almost like a kind of tit-for-tat move, one that seemed to go after Erdogan and the AKP where it hurt most: family ties and deals in the construction sector, which over the last decade has become a major source of revenue and prestige for the government and one of the principal ways it has built its patronage network. It was certainly no accident that among those arrested was Ali Agaoglu, a real estate tycoon closely connected to Erdogan who, as the Wall Street Journal put it, “represents a new class of ultrawealthy entrepreneurs that emerged under AKP's rule.”

The question hanging over Turkish politics is where does this all go next? Pro-Gulen media have hinted that there is more dirt to be uncovered, likely sending a warning to Erdogan – who built the AKP into the powerhouse that it is by declaring that it would be free of the corruption that tainted Turkish political parties of the past – not to strike back against it. The government, meanwhile, has moved swiftly to limit the damage, reassigning several police chiefs who were involved in the investigation. Erdogan, sticking to the script developed during the Gezi period, lashed out at the graft probe, calling it a conspiracy with domestic and international support from “some people backed by dark circles, gangs, media or capital owners.”

The bigger question, though, is what does this mean for Erdogan and the AKP’s future. Writing for the Al Monitor website, Turkey expert Henri Barkey suggests the PM, despite the scandal, remains powerful, yet is also potentially vulnerable:

Erdogan is likely to survive this crisis. He is still far too powerful and popular and controls vast chunks of the media today. He has been diminished and the investigation may ensnare other higher-ups. Crisis management, as seen in the Gezi protests, however, is not his and his party’s strong suit. Both are likely to commit more errors, especially if they persist in believing in the machinations of evil cabals. Bad analysis produces bad policy outcomes.

Certainly, the AKP remains the most popular party in Turkey and Erdogan the country’s most popular politician. But the increasing paranoia shown by some in the party’s leadership, seeing an effort to topple it around every corner, doesn’t bode well for a healthy future for the party. And with his response to the bribery scandal – charging the same police that he praised during the Gezi protests as now being under the control of international elements, claiming the same prosecutors who brought the military to heel through the Ergenekon and Balyoz cases are now being driven by political considerations – Erdogan opens up some of his and the AKP’s past actions for new scrutiny. Furthermore, a move by Erdogan towards more autocratic measures, in an effort to subvert further corruption investigations or to limit the power of the Gulen movement, could rattle foreign investors and threaten to undermine the already slowing Turkish economy, something which could cast the PM and the AKP in an even more negative light.

Prior to the 2011 elections, Erdogan’s associates said this upcoming period was going to be his “usta,” or “master” session, suggesting that this would be the time during which the PM, free of all the obstacles that stood before him in the past, would cruise towards the presidency and his coronation as the undisputed heavyweight champ of Turkish politics.

Erdogan may still rank above the rest of Turkey’s politicians, but he is also significantly more bruised and battered than he expected to be at this point. Yes, he remains the “usta,” but his supporters never thought he would have to fight so hard to prove his mastery of Turkish politics, in a bare knuckles battle that clearly has just begun.