  The structure and kinematics of the old component of the Galactic bulge are
still a matter of debate. The bulk of the bulge as traced by red clump stars
includes two main components, which are usually identified as the metal-rich
and metal-poor components. They have different shapes, kinematics, mean
metallicities, and alpha-element abundances. It is our current understanding
that they are associated with a bar and a spheroid, respectively. On the other
hand, RR Lyrae variables trace the oldest population of the bulge. While it
would be natural to think that they follow the structure and kinematics of the
metal-poor component, the data analysed in the literature show conflicting
results. We aim to derive a rotation curve for bulge RR Lyrae stars in order to
determine that the old component traced by these stars is distinct from the two
main components observed in the Galactic bulge. This paper combines APOGEE-2S
spectra with OGLE-IV light curves, near-IR photometry, and proper motions from
the VISTA Variables in the V\'ia L\'actea survey for 4197 RR Lyrae stars.
Six-dimensional phase-space coordinates were used to calculate orbits within an
updated Galactic potential and to isolate the stars. The stars that stay
confined within the bulge represent 57% of our sample. Our results show that
bulge RR Lyrae variables rotate more slowly than metal-rich red clump stars and
have a lower velocity dispersion. Their kinematics is compatible with them
being the low-metallicity tail of the metal-poor component. We confirm that a
rather large fraction of halo RR Lyrae stars pass by the bulge within their
orbits, increasing the velocity dispersion. A proper orbital analysis is
therefore critical to isolate bona fide bulge variables. Finally, bulge RR
Lyrae seem to trace a spheroidal component, although the current data do now
allow us to reach a firm conclusion about the spatial distribution.
