Abdullah Gul, the Turkish president, is also on the prosecutor's list.
Erdogan told The Hurriyet, a Turkish daily newspaper: "The Turkish Republic is our firmament.
"The column that supports it is union and unity; if it collapses, we will all be trapped underneath," he said.
The case highlights the political rift between Turkey's secularist circles, mostly active in the judiciary, military and academia, and the ruling party, whose many members are devout Muslims with ties to the country's Islamist movement.
The court sitting came shortly before bomb blasts that rocked Istanbul late on Sunday evening, that left at least 11 civilians dead and 70 wounded.
The ruling party and the secularist opposition were locked last year in a dispute over who should be Turkey's president, a largely symbolic post. However, the AKP won that round by easily winning a quick election.
The party later attempted to lift a decades-old ban on the wearing of head scarves at universities, but the top court overturned the bill, saying it was anti-secularist.
Dozen parties banned
Abdurrahman Yalcinkaya, the chief prosecutor, cites the head scarf bill as proof that the government is trying to scrap secularist principles enshrined in the constitution.
The court has banned two dozen political parties since it was established in 1963.
Now, with the highest court convening to look exclusively into the case until a decision is made, the fate of the party could be sealed as early as this week.
Observers say outlawing the party could plunge Turkey into political chaos, impact membership talks with the European Union and hit the economy at a time of global financial jitters and rising energy prices.
Shutting down the ruling party could force quick elections and unsettle markets as well as damage ties with the European Union.