  We present 20 newly discovered candidates for binary systems with an RR~Lyrae
companion. Using the photometric data from the Optical Gravitational Lensing
Experiment (OGLE) and Korea Microlensing Telescope Network (KMTNet) for the
Galactic bulge, we searched for binary candidates among non-modulated
fundamental-mode RR~Lyrae variables. We constructed and investigated over 9000
$O-C$ diagrams for individual pulsators, in order to find signs of the
light-travel time effect. We found 20 variables exhibiting cyclic variation in
the $O-C$ (time of the observed minus calculated brightness maximum) diagram,
which can be associated with a second component in the system, but for
confirmation of binarity, a long-term radial velocity study is necessary. The
modeling of the $O-C$ diagrams yields orbital parameters, estimates of the
semi-amplitude of the radial velocity curve, and the mass function. The orbital
periods of our candidates range from 3 to 15 years. Two of the binary
candidates display a minimum mass higher than the assumed mass of the RR~Lyrae
component, which points towards an evolved companion that can under some
circumstances contribute significantly to the total light of the system.
