We report photometric observations of the trans-Neptunian object 2004 TT _ { 357 } obtained in 2015 and 2017 using the 4.3 m Lowell ’ s Discovery Channel Telescope . We derive a rotational period of 7.79 \pm 0.01 h and a peak-to-peak lightcurve amplitude of 0.76 \pm 0.03 mag . 2004 TT _ { 357 } displays a large variability that can be explained by a very elongated single object or can be due to a contact/close binary . The most likely scenario is that 2004 TT _ { 357 } is a contact binary . If it is in hydrostatic equilibrium , we find that the lightcurve can be explained by a system with a mass ratio q _ { min } =0.45 \pm 0.05 , and a density of \rho _ { min } =2 g cm ^ { -3 } , or less likely a system with q _ { max } =0.8 \pm 0.05 , and \rho _ { max } =5 g cm ^ { -3 } . Considering a single triaxial ellipsoid in hydrostatic equilibrium , we derive a lower limit to the density of 0.78 g cm ^ { -3 } , and an elongation ( a/b ) of 2.01 assuming an equatorial view . From Hubble Space Telescope data , we report no resolved companion orbiting 2004 TT _ { 357 } . Despite an expected high fraction of contact binaries in the trans-Neptunian belt , 2001 QG _ { 298 } is the unique confirmed contact binary in the trans-Neptunian belt , and 2004 TT _ { 357 } is only the second candidate to this class of systems , with 2003 SQ _ { 317 } .