The California Teachers' Association has given another $2 million to the No on Proposition 32 campaign over the last 10 days, bringing the union's total spending to fight the measure to more than $20 million.
That's 40 percent of the $50 million the No on 32 campaign has raised so far.
Tuesday's filings with the Secretary of State also show that several firefighter unions contributed about $140,000. The San Diego Firefighters Local 145 gave a little over half the total, $73,260.
Contributions to the campaign and independent committees supporting Proposition 32 total are approaching $30 million, with the majority of that money coming from Republican activist Charles Munger Jr. Most of Munger's donations, however, have gone into a dual purpose independent committee that is also opposed to Gov. Jerry Brown's tax measure, Proposition 30.
Labor organizations have gone all-in to defeat Proposition 32, which would ban unions and corporations from using payroll-deducted money for political purposes and deny both groups from giving money directly to candidates or their campaign committees.
Both could still donate unlimited sums to independent expenditure campaigns, which are considered a constitutionally-protected form of free speech. But unions wouldn't have as much money to spend, since in California they raise their funds almost exclusively through payroll-deducted member dues. Corporations get their money from individual donations and their company treasuries.