  RX J1301.9+2747 is a unique active galaxy with supersoft X-ray spectrum that
lacks significant emission at energies above 2 keV. In addition, it is one of
few galaxies displaying quasi-periodic X-ray eruptions that recur on a
timescale of 13-20 ks. We present multi-epoch radio observations of RX
J1301.9+2747 using GMRT, VLA and VLBA. The VLBA imaging at 1.6 GHz reveals a
compact radio emission unresolved at a scale of <0.7 pc, with a brightness
temperature of T_b>5x10^7 K. The radio emission is variable by more than a
factor of 2.5 over a few days, based on the data taken from VLA monitoring
campaigns. The short-term radio variability suggests that the radio emitting
region has a size as small as 8x10^{-4} pc, resulting in an even higher
brightness temperature of T_b ~10^{12} K. A similar limit on the source size
can be obtained if the observed flux variability is not intrinsic and caused by
the interstellar scintillation effect. The overall radio spectrum is steep with
a time-averaged spectral index alpha=-0.78+/-0.03 between 0.89 GHz and 14 GHz.
These observational properties rule out a thermal or star-formation origin of
the radio emission, and appear to be consistent with the scenario of episodic
jet ejections driven by magnetohydrodynamic process. Simultaneous radio and
X-ray monitoring observations down to a cadence of hours are required to test
whether the compact and variable radio emission is correlated with the
quasi-periodic X-ray eruptions.
