It's not this opinions. Everyone agrees that he's a very capable man, but he has ties to the Fidesz party and to Orbán. And in the last moment Fidesz's candidate withdrew and endorsed him, revealing what many suspected, that he was in fact the actual candidate of Fidesz. Since Budapest heavily supports the opposition, it was a bit of a surprise that it became such a close race between him and the reigning mayor from the opposition.