The event will be in the Tucson Convention Center, and doors open at 4:30 p.m. (RSVP for free tickets here.)
Arizona is a must-win state for Bernie Sanders. Without it, his chances of winning the Democratic nomination are slim, political experts say, which explains why his campaign is pouring tons of energy and money into the state.
Sanders has released English and Spanish radio and TV ads, and his strong ground campaign is full of volunteers who have been canvassing and calling potential supporters relentlessly.
Arizona is one of three states and a territory holding primaries on Tuesday, and with 85 delegates on the line, represents the biggest prize of the day. (Voting are Utah with 37 delegates, Idaho with 27 delegates, Alaska with 20 delegates, and America Samoa with nine delegates.)
According to one poll, Clinton will win in Arizona if young people don't come out to vote, but based on the youthful and energetic crowd at this week's Phoenix rally, that seems an unlikely scenario. What's more, the New York Times FiveThirtyEight blog is reporting that Sanders stands a chance of winning the majority of Arizona's delegates.
So while many of Arizona's delegates are up in the air, what is clear is that these next few days are going to be chock full of political ads, rallies, and a lot of national media coverage. Prepare yourself for the homestretch.
Can't make tonight's Flagstaff rally? You can live-stream it here.