The viscoelastic properties are investigated for a side-chain liquid crystalline polymer using dynamic mechanical analysis (DMA) in the temperature region comprising the glass transition and the smectic phase. Two main relaxation processes are found, labeled alpha and delta relaxations, with increasing temperature. The results are compared with dielectric relaxation spectroscopy (DRS) and differential scanning calorimetry (DSC) results previously reported. The alpha-relaxation is well described by the KWW and Havriliak-Negami models, featuring a broad distribution of relaxation times, which depend on temperature according to the VFT model above T-g. The mechanical, dielectric, and calorimetric results in the region of the a-relaxation show similar behavior, indicating that this process should be assigned to the segmental mobility of the main chain. This hypothesis could be consistent with the onset of faster modes within the mesogens, mainly involving their transverse dipole component, for the case of the dielectric response of the alpha-relaxation. The delta-relaxation detected by both DMA and DRS has a similar origin, exhibiting a nearly Debye behavior. This process involves the motions of the bulky mesogenic groups and is not visible by DSC, as the increase of entropy during its occurrence is not significant.