  The only well-studied red nova progenitor (V1309 Sco) was a contact binary
with a 1.4-day period. The prospects for searching for similar systems, as well
as stellar merger candidates in general, are explored in this work. The
photospheric temperatures of 128 variables with periods P = 1.1 - 1.8 d
classified as W UMa-type binaries are calculated using their colors listed in
the SDSS catalog. A selection of 15 contact binaries with similar temperatures
and periods as the V1309 Sco progenitor is thus compiled. The Kepler Eclipsing
Binary Catalog is used to analyse systems with eclipse timing variations (ETV)
possibly caused by changes of the orbital period. Out of the 31 systems with
parabolic ETV curves listed by Conroy et al. (2014, AJ, 147, 45) two could be
contact binaries with a decreasing period and, therefore, potential stellar
merger candidates. Out of the 569 contact binaries in the OGLE field analysed
by Kubiak et al. (2006, AcA, 56, 253) 14 systems have periods longer than 0.8 d
and a statistically significant period decrease.
