If you listen to the Prime Minister and his Treasurer, the weekend byelection in the Melbourne seat of Batman was a “race to the left” and of no real consequence to the rest of the country.

Except in one key issue, it wasn’t.

Labor’s Bill Shorten has stolen the Liberals’ clothes and they apparently haven’t got goosebumps yet. He is now claiming the mantle of protector of the Catholic education sector with its hundreds of low-fee primary and secondary schools.

The Labor leader agrees with the sector that the Turnbull education funding reforms have “robbed” the Catholics of $250 million or a 12 per cent cut over the next two years.

Mr Shorten is promising to restore it and the $17 billion taken from government and Catholic schools over the next 10 years. The richer independent schools have seen their funding cut by only 2 per cent.

And don’t worry, he can pay for it with his reforms to multibillion-dollar tax concessions like dividend imputation cash rebates along with capital gains tax and negative gearing adjustments.

The Batman result suggests voters are more exercised by bread and butter issues like education and transport than they are by how Mr Shorten plans to pay for them.

While Labor chose an excellent candidate in former left-leaning union leader Ged Kearney, the Catholic school vote was no doubt also a key factor in Labor’s victory. More accurately, the votes of a huge swag of the 5000 parents who send their kids to Catholic schools in the electorate.

Mr Shorten has made no secret of his courting of the biggest provider of education in the country after government. Earlier this month he wrote to the president of the Catholic Bishops Conference – who just happens to be Archbishop of Melbourne Denis Hart.

Archbishop Hart’s Catholic Education Melbourne (CEM) is the most militant in the sector nationally. Its director, Stephen Elder, a former state Liberal politician, wrote to every one of his schools’ parents in Batman.

The letter evaluated the education policies of Labor and the Greens and found the Greens unwilling to address the funding issue beyond their policy “of redirecting funding away from some Catholic schools” and wanting to interfere in faith-based hiring policies.

The CEM letter was followed up with 30,000 robocalls to practically every household in the electorate in the last week of the campaign. The southern end of the electorate, populated with young families – many who voted Green at the general election – swung dramatically in some booths to Labor.

A quarter of the electorates’ kids go to Catholic schools. One mother told The Australian she and her husband usually voted Green but with the school her children attend facing funding cuts “you try do something about it”.

Education Minister Simon Birmingham accused Mr Shorten for abandoning principle in a naked grab for votes.

“There’s always somebody who can be bought for a few pieces of silver,” he said.

Senator Birmingham is looking at the socio-economic score (SES) calculations that somehow finds parents who send their children to some of the country’s most elite private schools are in more need of federal funding support than government and Catholic systemic schools.

Former prime minister Tony Abbott sees a major problem for the government if Senator Birmingham doesn’t fix it. He told 2GB: “If the government was smart we would have a look at our existing policy.”

Liberal and National MPs in marginal seats around the country would be hoping Mr Abbott’s warning is heeded.

Bill Shorten won’t be losing any sleep if it isn’t.

Paul Bongiorno AM is a veteran of the Canberra Press Gallery, with 40 years’ experience covering Australian politics.