The incumbent says the former Hewlett-Packard Co. CEO will promote a return to Bush-era policies she said led the country into recession.
The three-term senator addressed The Commonwealth Club in San Francisco on Tuesday, while Fiorina spoke about economic issues in Fresno.
Boxer says 23 million jobs were created during the Clinton administration, compared to 1 million under President George W. Bush. She noted that was the worst record since Herbert Hoover, who was president at the start of the Depression.
A Fiorina spokeswoman responded by saying Boxer "is busy blaming everyone but herself" for the state of economy.
The debate is Wednesday night at 7 p.m. at St. Mary's college.
Fiorina announced last week that she will travel to Israel the weekend following the debate.
Fiorina said she's going to brush up on her foreign policy credentials pver the Labor Day weekend.
The Republican Jewish Coalition is paying for the four-day trip.
Boxer, who is Jewish, has strong support among pro-Israel groups.
Before the primary, Fiorina criticized her GOP opponent Tom Campbell for opposing increased economic aid to Israel while he served in Congress.