Hillary Clinton has invented a bogus way of counting support—the popular vote in primaries. In an interview with Rachel Maddow, Clinton said "If I have more popular votes and more delegates, then I think it's pretty clear that the people who turned out and voted chose me to be the nominee." Introducing the idea of the "popular vote" into a system which includes caucuses as well as primaries is a false method of calculating support. It discounts states that use the caucus system and thus biases the results in Hillary's favor. The caucus system is a perfectly legitimate method of choosing candidates but the turnout is much lower than in a primary.
We should also realize that the number of pledged delegates won during the primary/caucus season should not be used as the sole measure of who will win the general election. For example, consider the fact that Independents cannot vote in many (closed) primaries. In the general election, a great many Independents will vote. Polls show that Bernie is much more popular than Hillary among Independents. Also, we should keep in mind that just because Hillary Clinton has done well in many red states does not mean those states will be in her column in November—red states almost always vote Republican.
And poll data that matches Clinton and Sanders against the Republican nominee should also be considered. Overall favorability of candidates needs to be factored in as well.