Prop 32 failed to meet passage at the ballot box on Tuesday. (Dawn Megli/Neon Tommy)

The measure was defeated by about nine percentage points with two-thirds of precincts tallied early Wednesday, leading labor leaders to say their fight to multimillion-dollar effort to defeat the measure had succeeded. unions, which rely on payroll-deducted dues, made an energized push to turn back the measure this year.

Union contributions to defeat Prop. 32 surpassed $60 million in a recent tally.

The California Teachers Association contributed more than $20 million to defeat Prop. 32, while the California State Council of Service Employees Issues Committee added another $8.2 million in donations.

Prop. 32 opponents saw the initiative as an attack on organized labor, since corporations are much more likely to raise political funds through corporate treasuries and executive contributions than payroll deductions. Voters rejected similar ballot measures in 2005 and 1998.

Support for Prop. 32 had been lagging during the weeks leading up to Election Day. A Public Policy Institute of California poll showed only 39 percent of likely voters supported the Prop. two weeks before the election, while 53 percent opposed it.

Yes on 32 channeled its support from wealthy donors like the American Future Fund, a conservative nonprofit organization with ties to the billionaire Koch brothers. Westco Financial Corp. CEO Charles Munger Jr. and Siebel System founder Thomas Siebel were also notable backers.

READ MORE ON PROPOSITION 32:

Propositions 30 And 32 Leave California Unions Stretched Thin

Prop 32: Labor Unions Seek To Fund Measure's Defeat

Prop 32: Campaign Finance Reform, Or Union Buster? 

Read more of Neon Tommy's coverage of the California Propositions here.

Reach Senior Staff Reporter Danny Lee here; follow him here.