Illawarra unions on Wednesday urged the Abbott government to commit to the full Gonski agreement as the bright green "I Give a Gonski" campaign van visited Wollongong.
The Coalition has committed to the need-based funding model for just four years, instead of the six promised under Labor.
Under the original agreement, schools would have received most of the funding in the final two years.
NSW Teachers Federation regional organiser Nicole Calnan said this meant schools would see only a third of the planned money.
"We are seeking a commitment from the Abbott government that come the federal budget in May, they will fund the fifth year and commit to funding the full six-year transition."
She said other unions had been supportive of the Teachers Federation's campaign since the beginning.
"It's an important issue for all unions, for their members, because it's their kids in schools that will benefit from the Gonski reforms."
South Coast Labour Council secretary Arthur Rorris called on the federal government to commit to six years of the Gonski agreement.
"It was one of the most broad-based and strongly supported community campaigns prior to the election and that's for a reason, everyone has a stake in it," he said.
The NSW Teachers Federation will hold a community forum on Gonski at the Kiama Leagues Club at 6pm on Thursday.