By Colette Hume BBC Wales education correspondent

Protesters have taken to the streets to try to save schools

It might seem like a simple equation, but it is one being fought against by parents across Wales.

Councils up and down the country are considering plans to close schools which are no longer cost effective.

With the 3 May assembly election just around the corner, those plans could have a real impact on the face of the next government of Wales.

Last April, proposals for the biggest school closure programme ever seen in Wales were thrown out by councillors in Cardiff.

Parents in the city mounted a powerful campaign targeting their local politicians. The threatened schools remain open for now, but the city still has the problem of 8,000 spare places costing council tax payers �3m a year.

If a poltical party says they'll keep our school open, we'll vote for them Carmarthenshire parent Jill Saracini

But it is not just parents in the cities who are turning the heat up on the politicians.

In Gwynedd, the council is holding a series of meeting with parents and local communities and Anglesey is consulting on the future of the island's primary schools.

Just 16 pupils go to Ysgol Mynyddcerrig in Carmarthenshire, but the parents and local community fought a vigorous campaign to save the school. It is due to close its doors for the last time in July.

Decisions to close schools are made by local authorities, not the assembly government, but parents in the village say they will use the vote to deliver a strong message about their community.

"The school is very important to us," said parent Jill Saracini.

"And I think there are lots of parents around Wales who feel the same way. If a poltical party says they'll keep our school open, we'll vote for them."

You could potentially see a very local situation magnifying itself at a national level Daran Hill, political consultant

So if Jill Saracini is right and parents across Wales do vote on the issue of schools, could they make a real difference to the election result?

Political consultant Daran Hill said that if parents did vote together in a block they could have a significant impact.

"School closures don't tend to happen in isolation," he said.

"Each child has one, two parents. You could potentially see a very local situation magnifying itself at a national level because some of those assembly majorities are very small."

So that leaves politicians with a dilemma: closing small schools saves money, but promising to keep them open seems to be a guaranteed vote winner.