Gun control, once a third rail, now a key issue as Democrats seek to control House

Two years ago, when Democrat Chrissy Houlahan began running for Congress, people told the military veteran and former high school teacher to stay away from one topic:

Gun control.

"There was a caution to me ... that it wasn't a quote-unquote winning issue," she recalled.

But she ignored the advice. And since she announced her candidacy, a rash of mass shootings, including the one in February in Parkland, Fla., have rocked the country. Supporting major gun-control policies, she has been endorsed by gun-safety groups and is favored to win a newly redrawn seat that in its last configuration has been long held by Republicans.