(CNN) Gun control activist Lucy McBath, whose son was shot and killed in 2012, will win the Democratic nomination in Georgia's 6th Congressional District, CNN projects.

McBath, who defeated businessman Kevin Abel in a runoff election, will now face Republican Rep. Karen Handel in November in a race that could show whether gun control is an effective issue for Democrats in wealthy suburban districts. The district hasn't elected a Democratic US representative since the 1970s.

Democrats also held a runoff in another congressional district where they hope a blue wave in November could help oust an incumbent Republican. In GOP Rep. Rob Woodall's 7th District, Georgia State University professor Carolyn Bourdeaux defeated David Kim, a tutoring business founder, CNN projects.

From gun control advocate to House candidate

McBath became a prominent spokeswoman for the gun control movement after her 17-year-old son Jordan Davis was shot and killed by a white man in 2012 after a dispute over loud music. She testified before Congress on the issue and also campaigned with Hillary Clinton in 2016 as part of the "Mothers of the Movement" — a group of women who lost children to police or gun violence.

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