"Like many other pollsters, we now also draw a sizable percentage of our daily sample survey results from special demographically balanced Internet Panels to capture the growing number of people who no longer have landline telephones. These panels are increasingly important because, unlike live-operator calls to cell phones, they both reach the younger demographic and do so while maintaining their personal privacy – just like in the voting booth."
https://www.rasmussenreports.com/public_content/about_us/faqs
I haven't a clue what internet panels are, but it has been factored in. Rasmussen also nailed the 2016 election results..