An aide to Energy Secretary Ed Davey has criticised the "nonsense" decision to exclude new-build homes and small businesses from a flood insurance deal.
The Government announced in June that it had finally reached agreement with the insurance industry to tackle fast-rising premiums just weeks before previous arrangements were due to expire.
But Liberal Democrat MP Stephen Gilbert - whose Cornwall constituency has been badly affected by flooding - said he was ready to fight for changes in the Water Bill when it is debated in the Commons.
A levy paid by household insurers into a fund will pay claims for people at a high risk of flooding.
The Department for Environment, Food and Rural Affairs said developers had been clearly warned in recent years not to build in flood-prone areas - meaning homes constructed from 2009 should not face high premiums and so could be excluded.
But Mr Gilbert - who is parliamentary private secretary (PPS) to Mr Davey - said that ignored the risks posed by climate change.
"It is clearly a nonsense to suggest that homes built since 2009 won't be covered," he told the Yorkshire Post.
"We know there has been some inappropriate development in flood risk areas - but what we also know is because of climate change there isn't an area of the country that isn't a potential flood risk area.
"We are going into a world where climate change makes many, many more homes open to flood risk.
"Flash flooding, atmosphere warming, more water held in the atmosphere - (it is) completely unpredictable about where it may fall down."
He later added: " Labour ducked the issue of sorting a sustainable and long term future for flood insurance and the coalition's proposals for Flood Re are a welcome step in the right direction.
"It's clearly important to ensure that small businesses run from domestic premises like B&Bs are covered as well as new-build homes and I will be engaging with ministers on these issues as the Bill goes through parliament."
Shadow environment secretary Mary Creagh said: "People in areas of high flood risk are being hit with higher insurance premiums and excesses because this out-of-touch Tory-led Government has failed over the last three years to renew Labour's deal on flood insurance.
"The Government's proposals raise serious questions about how who will be covered, how much householders will pay into the Flood Re scheme, the costs of flood insurance premiums and who picks up the bill in the event of a catastrophic flood in the early years of the scheme.
"They require urgent answers to ensure Flood Re is built to last."