"Possible coordination" means that there is a chance or likelihood that people or groups are working together or cooperating to achieve a common goal or objective. Full definition
Several Republicans joined them in raising alarms of how it could affect probes into possible coordination between Trump associates and Russia to influence the 2016 presidential election. (fortune.com)
Trump and his allies have seized on Uranium One as Mueller's investigation into the president's possible coordination with Russia to swing the 2016 election in his favor heats up. (businessinsider.com)
Mueller has so far charged four people in his investigation of possible coordination between the Trump campaign and Russian officials, most recently former national security adviser Michael Flynn. (washingtonpost.com)