The claim regarding a structural budget deficit of $20-$30 billion and state officials admitting uncertainty about General Fund spending on salaries is not corroborated by the provided web search results. The web search results provided general information about California's economy and Newsom's actions, but none specifically confirm the deficit range or the admission of uncertainty regarding salary spending.

The claim that the LAO reported a $100 billion increase in state revenue since 2019 is not independently corroborated by multiple sources. The provided web search results mention the LAO advising on fiscal issues and the concept of structural imbalance, but none confirm the specific figure of a $100 billion revenue increase since 2019.

The claim that 70% of the $100 billion increase in spending was used to maintain existing services (e.g., Medi-Cal, K-14 education, developmental services, and in-home supportive care) is not corroborated by multiple sources. The provided web search results do not contain the specific breakdown of spending percentages or the list of programs mentioned.

The claim that the remaining 30% of the $100 billion increase in spending included expansions for university funding, childcare, police oversight, firefighting services, and Medi-Cal coverage (including for undocumented immigrants) is not corroborated by multiple sources. The provided web search results do not contain the specific breakdown of the 30% spending increase or the list of programs mentioned.

The claim that the LAO estimated that eliminating all discretionary expansions adopted since 2019 would save approximately $15 billion is not corroborated by multiple sources. The provided web search results do not contain the specific $15 billion figure or the context of eliminating discretionary expansions.

The claim that the LAO stated that the state cannot definitively determine how much General Fund money is spent on salaries or benefits, or how many full-time equivalent positions are filled using General Fund resources is not corroborated by multiple sources. While the web search results confirm the LAO's role in advising on fiscal issues, they do not contain this specific quote or finding.

The claim regarding Professor Thad Kousser's prediction that Newsom and the Legislature will almost certainly pass a balanced budget by June 15, potentially using 'gimmicks' is not corroborated by multiple sources. The web search results provide general information about political science and politics but do not mention this specific prediction or the professor's name.