${\mathrm{VO}}_2$ features concomitant structural and metal-insulator transitions. This poses a challenge for understanding the underlying mechanism: Is the transition triggered by a structural or by an electronic instability? The two scenarios are expected to produce very different pretransitional fluctuations above $T_{\mathrm{C}}$. By combining magnetic susceptibility, IR reflectivity, and x-ray diffuse scattering measurements, we observe that metallic ${\mathrm{VO}}_2$ features strong electronic and structural fluctuations toward the insulating monoclinic phase. By measuring resonant diffuse x-ray scattering across the vanadium $K$ edge, we search for a potential decoupling between electronic and structural ordering in these fluctuations, finding no evidence of it. While our results do not completely rule out pure electronic fluctuations, they constrain them, favoring the interpretation that the ${\mathrm{VO}}_2$ metal-insulator transition is triggered by a structural instability. Our work offers a unique approach to solve similar problems in other strongly correlated systems.

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• Peierls transition
• Phase transitions
• Phonons
• Mott insulators
• Single crystal materials
• Strongly correlated systems
• Susceptibility measurements
• X-ray absorption spectroscopy
• X-ray diffraction