"We are tired of hearing about who will replace Assad," Erdogan said during a visit to Brussels.
"If Assad leaves, the will of the people will rule Syria.... There cannot be anything worse than this government or any tragedy worse," he said after meeting top European Union officials.
Erdogan said the latest reports of atrocities blamed on Assad showed how bad the situation had become in Syria, where rebels, backed by Turkey among others, have become bogged down in efforts to oust the president.
The Turkish premier highlighted how much his country has done in helping about 700,000 refugees from Syria at a cost of some USD 2 billion so far.
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"Unfortunately, we only have got $130 million from the international community," he said, suggesting that others were not fully aware of the burden on Turkey.
Erdogan said he hoped the Geneva II conference beginning this week in Switzerland would produce a solution to the Syria conflict.
Assad has made clear he has every intention of remaining in power.
Syria was a key talking point for Erdogan as he met European President Herman Van Rompuy and European Commission head Jose Manuel Barroso in Brussels for talks on reviving Turkey's negotiations toward joining the EU.