  A novel model of particle acceleration in the magnetospheres of rotating
active galactic nuclei (AGN) is constructed.The particle energies may be
boosted up to $10^{21}$eV in a two step mechanism: In the first stage, the
Langmuir waves are centrifugally excited and amplified by means of a parametric
process that efficiently pumps rotational energy to excite electrostatic
fields. In the second stage, the electrostatic energy is transferred to
particle kinetic energy via Landau damping made possible by rapid "Langmuir
collapse". The time-scale for parametric pumping of Langmuir waves turns out to
be small compared to the kinematic time-scale, indicating high efficiency of
the first process. The second process of "Langmuir collapse" - the creation of
caverns or low density regions - also happens rapidly for the characteristic
parameters of the AGN magnetosphere. The Langmuir collapse creates appropriate
conditions for transferring electric energy to boost up already high particle
energies to much higher values. It is further shown that various energy loss
mechanism are relatively weak, and do not impose any significant constraints on
maximum achievable energies.
