The coalition government is being urged to set up an independent commission to look into why Cornwall gets less public money than many other parts of the UK.
The county's three Liberal Democrat MPs have signed a Commons motion saying Cornwall has suffered decades of under-funding from consecutive governments.
St Austell & Newquay MP Steve Gilbert, North Cornwall's Dan Rogerson and St Ives' Andrew George wrote the motion.
They said underfunding meant the county was one of the poorest parts of Europe.
In the motion, they have warned that the situation could get worse with ministers planning to make major public spending cuts in an effort to reduce the UK's budget deficit.