Boxer was invited but declined. The Democrat was in Palo Alto touring a new veterans' mental health center.
The poll shows Fiorina is in the lead with 47 percent to Boxer's 42 percent. Five percent of the voters are undecided.
"Certainly, we're encouraged by that poll and others," Fiorina said. "What those polls and others demonstrate is that people are paying attention and figured out Barbara Boxer's policies aren't working."
"We don't know that we're down," Boxer said. "This poll shows me down. Other polls show me up. We think it's close, we really do. We're going to have to fight hard."
The poll shows that Boxer has an edge with Hispanics and black voters statewide, while Fiorina leads among whites and Asian voters.
There is every indication it will be a tough fight. Jobs and job creation are at the center, with Fiorina accusing her opponent of supporting worthless administration subsidies.
"With all due respect, the junior senator from California Barbara Boxer has not helped small business ever," Fiorina said.
Boxer has said that the billions in bailout money have created jobs and restored business. She has a ready retort for the former head of HP.
"She was fired as head of HP, she shipped 30,000 jobs overseas," Boxer said. "People don't know this yet. So, our campaign is extremely energized, we have almost 100,000 donors, we're very excited and people will know what the choice is."
Boxer has dropped three points since the last SurveyUSA poll in July. Fiorina has been relatively flat, but her strongest support comes in the Central Valley where she has surged from a 7-point lead to 21 points in Thursday's poll.