Staffs and pupils wanted to must raise £7,500 by February to meet their target or they will lose the £21,500 that has already been pledged due to the crowd funding system.
The minibus used by Uplands Junior School, in Finchfield, Wolverhampton, was stolen last year.
And the school has been working to raise £29,000 to fund a replacement.
The bus was never recovered, so the school has been having to hire transport, or rely on parents and staff, to transport the children safely to and from school trips.
As this began eating into the cash-strapped school's funds, staff and pupils decided to start their fundraising campaign, which has been backed by Finchfield and Castlecroft Community Association.
Andrew Atkinson, chair of the community association, said: "Uplands is a school in our area of concern and we heard the loss of the minibus was causing them serious problems.
"When we heard about it we wanted to help them so they could raise the funds to buy a brand new minibus, now we're appealing to everyone to help us raise the final amount."
The campaign has now been backed by the Mayor of West Midlands, Andy Street, who visited the school to meet the schoolchildren and discuss the fundraiser.
He said: "It's brilliant to see the children coming together with lots of ideas of how to raise this money.
"It's inspiring to see what the youngsters are working on together all for the good of their community."
The insurance payout did not cover the full cost, so have been hosting various activities including discos, own clothes days and Christmas fairs to raise the remaining funds.
Wolverhampton Council has pledged £2,929 and the ward councillors of the area have pledged a further £2,166.
Headteacher, Suzanne Webster-Smith, said: "We're incredibly grateful for the support from our community, it's really enthusing the children and inspiring them.
"We're determined to reach our target of £29,000 and with everyone's support we will get there."
The community association is also calling on businesses to pledge any amount they can spare towards the campaign.
The deadline for donations is February 14, 2020, and they can be made on the school's Spacehive fundraising website.