Democratic Senate candidates Ed Markey and Seth Moulton clashed in their final debate before Massachusetts' 1 September primary, each seeking to convince voters in the heavily Democratic state that they are the stronger standard-bearer for progressive priorities. The Thursday night debate underscored an intensifying fight within the party over its ideological direction, as both candidates sought to outflank each other from the left ahead of a closely watched primary contest.

The debate touched on several contentious issues, including transgender athletes' participation in sport, calls to abolish Immigration and Customs Enforcement (ICE), socialism, and congressional term limits. Incumbent Senator Markey faced a challenge from Congressman Moulton, with both men pressed on where they stand on these flashpoint topics as they competed for the support of the state's progressive electorate.