Docters van Leeuwen, 61, might already quit in October, in order to be available as a member of parliament for the liberal party VVD, he indicated during a recent meeting with AFM staff.
Earlier, the chairman had said not to be available for a third four-year term at the AFM, when the present one ends halfway 2007. In the meantime, the collapse of the Dutch cabinet has triggered new elections as early as November.
Docters van Leeuwen's early departure will however depend on being placed on the VVD's list of candidates, he has made clear. The list is due to be published at the end of August.
Under Docters van Leeuwen the AFM has grown from a small equity trading watchdog into a sector-wide regulator. It now also covers securities-related market conduct supervision and communication for pension funds.
According to a AFM spokeswoman, no decision has yet been taken on a successor.
Docters van Leeuwen also chairs the Committee of European Securities Regulators. He will give up this post when he leaves the AFM.
Docters van Leeuwen is a fomer head of the Dutch Secret Service and chairman of the national board of Attorneys General.
Last month the AFM said dozens of Dutch pension funds still don't fully comply with its market conduct rules.