The firms were chosen for their extensive experience in polling and because they do not currently work for any candidates seeking statewide office in California.
Public Opinion Strategies, founded in 1991, has polled for news organizations and Republican candidates in all 50 states. It was the primary polling firm for Sen. John McCain's presidential campaign.
Greenberg Quinlan Rosner's chairman, Stan Greenberg, was President Clinton's pollster for his campaigns and during his presidency. The firm has polled for Democratic candidates across the country and foreign leaders, including Nelson Mandela, Tony Blair and former Israeli Prime Minister Ehud Barak.