Proposals for thousands of new homes on green belt land in Hertfordshire go before a public inquiry on Tuesday.
The expansion plans have been criticised by campaigners
Developers want to build 5,000 new houses west of the A1M at Stevenage.
Stevenage Borough Council believes the town is desperately in need of a major urban extension.
But environmental campaigners against the expansion are keen to protect Stevenage's green belt from what they see as unnecessary development.
Peter Lilley, MP for Hitchin and Harpenden, is set to oppose the plans at the public inquiry.
He told the BBC he had spoken out against previous attempts to develop this part of the green belt.
"On every occasion we have defeated the proposals and I hope we maintain that record this time," said Mr Lilley.
The public inquiry is expected to last until the end of May.