The hearing is scheduled from 1 to 5 p.m. at the Junipero Serra State Office Building, 320 W. 4th St. in Los Angeles.
Florio on Friday submitted an alternative proposal to the full commission to deny Comcast's request to take over the licenses held in California by Time Warner Cable and Charter Communications.
"This transaction is not in the public interest," Florio's proposal said.
The PUC has scheduled a May 21 vote on the proposed media merger.
Two months ago, a proposal favorable to Comcast was submitted to the panel. That means there are competing proposals.
Administrative Law Court Judge Karl Bemesderfer in February recommended the PUC approve the Comcast merger, saying the deal was in the public interest.
Bemesderfer, however, added a lengthy list of suggested conditions, including requiring that Comcast work diligently to expand high-speed Internet access to low-income residents in Los Angeles and other counties in California.
Florio, for his part, listed several potential harms that could accompany the proposed merger, including concerns about privacy and a shortage of competition in the state for high-speed Internet service.
The merger, if approved, would increase Comcast's service footprint to about 80% of the state.
Comcast, for its part, has argued that it doesn't compete in the same geographic regions as Time Warner Cable, and thus consumers would have the same number of choices for providers.
"We continue to believe the administrative law judge’s decision, reached after months of briefings, analysis, and careful consideration, has properly recommended approval of the Comcast-Time Warner Cable-Charter transaction," Bryan Byrd, a Comcast spokesman, said in a statement.
Comcast needs the PUC's blessing for the deal because the group regulates cable TV and phone service in California.
The Federal Communications Commission and the U.S. Department of Justice separately are reviewing the proposed merger, which would give Comcast nearly 30 million customers nationwide. It would have nearly 1.8 million customers in Greater Los Angeles.
Comcast hopes to prevail and complete the merger this summer.