In a stark closing argument ahead of the US midterm elections, President Joe Biden warned that a Republican victory could weaken the country's democratic institutions and undo much of his presidency’s accomplishments.

With a stack of pamphlets under her arm, Dawnee Giammittorio -- who has been a gun control activist since her sister-in-law was shot dead -- goes door-to-door in northern Virginia, hoping to help flip control of Congress back to the Democrats.