Shannon Watts is the founder of Moms Demand Action for Gun Sense in America. The opinions expressed in this commentary are solely her own. View more opinion articles on CNN.

(CNN) On Tuesday night, after years of making incremental gains, Virginians finally elected a gun sense majority in both houses of the General Assembly.

Voters went to the polls and held their lawmakers accountable for failing to address the gun violence crisis that has traumatized community after community in the Commonwealth. And polling throughout the election showed that gun safety was the defining election issue that energized voters.

Virginia already has a governor who is ready and waiting for the new General Assembly to pass good gun bills that he can sign into law.

And these stronger gun laws could save an untold number of lives, in the Commonwealth and beyond. Loopholes in Virginia's laws have made it a major feeder of crime guns into the country's "Iron Pipeline," the route used to traffic firearms up and down the I-95 corridor. Between 2013 and 2017, nearly 16,000 crime guns that originated in Virginia were recovered in crimes in states outside of Virginia -- and more than 12,000 of these crime guns were traced in states that have comprehensive background check laws.

Research shows that just by closing the loophole in Virginia's laws that allow unlicensed gun sales without a background check, gun trafficking could be reduced by 48% in cities and by 29% across state lines.

For years however, Virginia Republicans largely refused to take action against gun violence, even though the vast majority of their constituents support stronger gun laws. And after the mass shooting in May at the Virginia Beach Municipal Center that killed 12 people and wounded four others, the Republican-led legislature sat on its hands. The governor called a special session specifically to address Virginia's gun violence crisis, but Republicans blocked any vote on gun safety and ended the session after just 90 minutes.

Republicans' abject failure to act outraged our volunteers. It became our mission to ensure this election was a referendum on gun violence.

According to a Washington Post-Schar School poll , gun safety was the single top issue for Virginia voters, ahead of even bread-and-butter topics like education, health care and the economy.

When I canvassed in cities across the state in October and again in early November, I heard over and over again that Virginians — regardless of their political affiliations — wanted to send a strong signal to both state and federal lawmakers: "Do the right thing and we'll have your back; do the wrong thing and we'll have your job."

And we backed up that demand with dollars and grassroots force. Everytown for Gun Safety spent $2.5 million on ads, direct mail, polling and contributions to gun sense candidates and political committees. Moms Demand Action volunteers made more than 100,000 calls, knocked on tens of thousands of doors, sent hundreds of thousands of texts and recruited volunteers across the country to call Virginia voters, too.

A retired volunteer couple in Fairfax spent the last few months going back and forth to Richmond to canvass in competitive legislative districts near the capital. Another volunteer from Loudoun attended numerous candidate forums to keep gun safety front and center for candidates, and tabled at farmers markets to encourage her community to vote.

And over in Montgomery County, Maryland, a volunteer helped organize nearly 20 events for out-of-state volunteers to contact Virginia voters and let them know the stakes of this election. She showed up to Virginia to knock on doors in the pouring rain and phone banked during the World Series.

And volunteers far away from Virginia — in places like Ohio, Nevada and Oregon — hosted phone banks, texted and wrote postcards to encourage Virginians to vote because they know guns travel across state lines as easily as cars do, and electing candidates who support stronger gun laws will make all Americans safer.

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And that's one more reason this win in the Virginia legislature was monumental: It serves as a warning to lawmakers running in 2020 who still side with the gun lobby — particularly US Senators who have gun safety bills on their desks but haven't acted — that their jobs are in jeopardy.

It also sends a strong signal to the more than 90% of Americans who support universal background checks that we can go toe-to-toe with the gun lobby and win, and we will fight like hell to do it again next year.

In 2019, we showed Virginia lawmakers what happens when they don't stand up for our families. And after this win, you can bet that in 2020 we'll be doubling down.