The suite of changes would constitute one of the most aggressive pieces of gun legislation in the country. Money has poured into the “Yes” campaign, a symptom of the frustration gun-safety advocates have felt with the pace of change in state and federal legislatures. Microsoft billionaire Paul Allen, who died Monday, donated over $1.3 million. Ultra-rich investor Nick Hanauer and his family have also dropped well over $1 million into the campaign. The measure has even gone national, catching the eye of former New York mayor Michael Bloomberg — his Everytown for Gun Safety PAC has given over $300,000.

In total, the Safe Schools Safe Communities committee fundraising on behalf of the measure has raised $4.6 million. This dwarfs the opposition, which has raised $316,000, almost half of which has come from the National Rifle Association.

Elway’s recent polling numbers are about in line with the final tally of a 2014 measure to expand background checks for person-to-person transfers of firearms, which passed with 59 percent. In 2016, a measure allowing family members to obtain firearm protection orders passed with 69 percent approval.

Support for initiatives often decreases as election day nears. Stuart Elway, the longtime pollster who conducted the statewide poll, has said that anything with less than 50 percent approval in pre-election data is therefore in danger. At 59 percent support, I-1639 has some cushion.

The proposed initiative comes as mass shootings have become increasingly deadly. Some of those shootings, such as the February shooting at Parkland High School in Florida that ended with the deaths of 17 students, spur activism and debate, but very few result in any change in gun policy. Washington state has been the site of numerous recent shootings, including one that occurred at a party in Mukilteo where three teenagers were shot and killed by an assailant using a Ruger AR-556 semiautomatic rifle. Paul Kramer, whose son was wounded in the incident, has since become one of the faces of I-1639.