New polling data from SurveyUSA shows growing support for Washington State’s marijuana legalization initiative, I-502.

The new survey found that 55 percent approve of the initiative, with just 32 percent opposed and 13 percent undecided. The poll was conducted from July 16th through 17th and involved 600 likely voters. You can read more about the SurveyUSA poll here. This is a significant upward swing in support for I-502, previous polling in June had only 50% of voters supporting Initiative 502 to 37% opposed.

The Seattle Times is also reporting that initiative proponents plan on kicking off a million dollar advertising campaign in August.