Powys County Council announced plans to close Churchstoke County Primary School earlier this year – along with four other Powys schools.
Local residents have launched a campaign to save the school and called on the authority to drop the proposals.
However, the council has now launched the formal consultation on its future – a significant step in the efforts to close the school.
The consultation will close on Wednesday, June 9.
The council has defended the move, saying the proposal has "not been reached lightly", but says it is the "best interests" of the pupils who attend the school.
Parents and local residents have dismissed those suggestions, with 1,448 people having signed the petition asking the council to drop the proposal.
Dr Caroline Turner, chief executive of Powys County Council, said: “We are committed to transforming the learner experience and entitlement for our learners and we will achieve this by delivering our Strategy for Transforming Education in Powys 2020-2030.
“Our strategy is ambitious, exciting and we believe it will give our learners the best possible start they deserve.
"However, as we start to implement it, we will be faced with significant decisions as we look to address some of the challenges facing education in Powys which include the high proportion of small schools in the county, decreasing pupil numbers and the high number of surplus places.
“This proposal has not been reached lightly but we have ensured that the best interest of the learners at this school were at the forefront of our discussions and decision-making.
“If this school is to close, then the learners would be attending schools that would be better equipped to meet the requirements of the new national curriculum and that could provide a wider range of educational and extra-curricular opportunities.
“However, it is important that the people of this school community as well as the wider area have their say on this proposal. I would urge them to send their views so that they can be considered.”
Under the council's plan the school would close at the end of August 2022 with pupils transferring to their nearest alternative school.
People can respond to the consultation at en.powys.gov.uk/transformingeducation
Alternatively people who want a paper copy of the consultation document can contact the Transforming Education Team by phoning 01597 826618 or emailing firstname.lastname@example.org
People can also respond in writing by emailing email@example.com or via post at Transforming Education Team, Powys County Council, County Hall, Llandrindod Wells, LD1 5LG.