(CNN) Kentucky Gov. Matt Bevin signed a controversial pension reform bill that is firmly opposed by a teachers' group, which has called for a "day of action" later this week.

The Kentucky Education Association urged its members to come to the state Capitol on Friday, in response to key decisions by the governor. It had called for teachers and supporters to rally at the state legislature, before Bevin signed the controversial pension reform, Senate Bill 151 into law on Tuesday.

In a message to teachers, KEA President Stephanie Winkler asked "each school district or citizen that can legally be in Frankfort, to be there" on Friday.

Last week, Kentucky teachers marched to the Capitol to denounce the pension bill and demand funding for schools to help pay for textbooks, technology and programs. On March 30, more than 20 county schools closed after teachers called out of work after lawmakers passed the pension bill.

Thousands of Kentucky teachers rallied at the state Capitol in Frankfort on April 2.

KEA opposes the pension reform, in which new hires will have to enter a hybrid cash balance plan, which differs from a traditional pension, and would limit new sick days that teachers can put toward their retirement. It also wants the state legislators to override Bevin's veto of a budget bill and a revenue bill, with Winkler saying if these two bills don't pass, "this is very bad news for public education."

Governor rips KEA as 'frauds'

After signing the pension bill Tuesday, Bevin called it "a very good bill" and criticized the KEA in an interview with WHAS Radio.

"They are absolute frauds," he said. "They are not looking out for the best interest of their teachers, they are looking out for the best interest of themselves. KEA leadership is a fraud."

When asked about the teachers' day of action on Friday, the governor replied: "If we want to punish students by having their teachers walk out on them because they are instructed to do so by the KEA, the KEA doesn't know which side of this they're on."

The Republican governor also blasted the group for supporting his Democratic predecessor, former Gov. Steve Beshear, whom he blamed for underfunding education during his two terms.

Bevin claimed to have put more money into teachers' plans and their pension than Beshear.

"I respect the teachers who go into the classroom and teach the students, and I'm grateful to them because eight of those students happen to be my kids. So I appreciate the kind of work that they are doing but the KEA where were they? What have they done with all of those teachers' dues except waste them supporting a governor who under-funded them and created this process," he said.

Supporters of pension reform have said that it's critical to fix the state's pension crisis, which ranks as one of the worst shortfalls in the US.

State lawmakers tucked pension reform into another bill about sewage and passed that bill, late last month -- a move that was heavily criticized by teachers.

Critics worry that hybrid plans, like the one approved, will lead to significantly lower benefits, which could be detrimental to those in a state like Kentucky where teachers don't pay into Social Security.

Kentucky Attorney General Andy Beshear, son of the former Kentucky governor, filed a lawsuit Wednesday challenging the bill after vowing to take action in a tweet posted Tuesday night.

"We have just learned that Gov. Bevin has signed SB 151 (pensions). When the courts open tomorrow, we will take action. Stay tuned." —Attorney General Andy Beshear — KY Attorney General (@kyoag) April 10, 2018

KEA urges member action

With only two days left in Kentucky's regular session, KEA wants its members to show up Friday to pressure lawmakers to override the governor's vetos of House Bill 200, which is about the budget and the House Bill 366, which concerns revenue.

"If they do not override these two bills (which are dependent upon each other to have a balanced budget) and they leave Frankfort without passing a budget this is very bad news for public education," said Winkler in a statement. "The lack of a state budget gives the Governor free reign to only spend what he deems are essential government services. This means that pension and/or public education funding would be in jeopardy."

Bevin vetoed the the two bills Monday, citing reasons such as "extremely bad taxes" and lack of balanced budget.

KEA says the bills aren't perfect, but that teachers must be "united to help protect public education funds at all costs."

"We need legislators to pass this budget. It is the difference between school system budgets in the red or being in the black, Winkler said.

House Bill 366 has come under criticism from Democrats and analysts who say that it favors the wealthy and corporations, reported CNN affiliate WKYT.