Volunteers for San Diego Democratic mayoral candidate David Alvarez were walking precincts in Rancho Bernardo this weekend, including Republican households. This is a curious move. Rancho Bernardo is about as red as you can get in the city of San Diego. Carl DeMaio got 80% in one precinct and got at least 60% in almost all of them.
I've walked precincts for candidates and it's rare that they're able to have enough volunteers to hand out all the packets in all the precincts. So you usually concentrate your walking in the neighborhoods that'll be most favorable to your candidate and include ones that are slightly less favorable and go down the line. If you have three hours to walk a neighborhood, you'll get a lot more votes knocking on a lot more doors in a favorable area.
This is a special election, which means it'll be lower turnout than 2012. This Alvarez precinct walking decision either means that Alvarez has a ridiculous number of volunteers and is covering every precinct in the city or that he's desperate and realizes he can't win counting on turn-out in heavily Democratic areas. Considering the new SurveyUSA poll has him trailing by a lot, I'd guess it's the latter.