Frederick is the Virginia-born son of a Colombian immigrant mother, and he hailed himself as the first Latino member of the Virginia House of Delegates where he represented Prince William from 2004 through 2009.
The claim to Hispanic roots could be important the expected light turnout for next week's off-off-year primary. Prince William and northern Virginia are home to significant immigrant communities.
So Munoz, in his first bid for elective office, challenged Frederick to a debate in Spanish. Frederick declined, accurately noting that the General Assembly conducts its business in English.
The winner of the Republican nomination meets Democrat Linda T. "Toddy" Puller, who is seeking her fourth term in a district made slightly more Democratic by this year's reapportionment. She gained a greater share of often conservative but sometimes politically volatile Prince William County.
But Prince William is also home to a U.S. Marine base at Quantico, a source of strength for the widow of Lewis Puller, a Marine hero whose wounds from a booby trap in Vietnam is recounted in the Pulitzer Prize-winning autobiography "Fortunate Son." Throughout her legislative career, she has been the Senate's most forceful and authoritative voice for veterans' issues.
State legislative primaries in Virginia draw the lowest turnouts of any election cycle. This year's turnouts could be even lower because delays necessitated by legislative redistricting pushed the primaries from their normal spot in early June into the height of vacation season.
Yet the primaries are important because they set the ballot for this fall's pivotal Senate races. Democrats control 22 of the 40 Senate seats, so a net gain of just two seats by the GOP gives them effective control of the Senate for the first time since 2007 because Republican Lt. Gov. Bill Bolling presides over the Senate and holds the tie-breaking vote.
A Senate majority would also put Republicans in charge of both chambers of the General Assembly and the governor's office, putting the party complete command of policymaking in Virginia for the first time since 2001 and allowing Gov. Bob McDonnell to enact the socially and fiscally conservative agenda he proposed as a candidate two years ago.
Bob Lewis has covered Virginia government and politics since 2000.