The establishment choice, former Virginia Lt. Gov. Don Beyer, has raised more than $1 million so far, the only one of the seven candidates to do so.
The winner of next Tuesday's primary is expected to easily win the general election against Republican Micah Edmond; President Barack Obama carried this liberal district 68 percent to Mitt Romney's 31 percent in 2012.
Beyer is facing state Sen. Adam Ebbin, the first openly gay member of the Virginia Legislature; radio talk show host and constitutional attorney Mark Levine; Virginia state delegate Patrick Hope; and three others.
The Northern Virginia district borders the nation's capital.