The Government is facing calls for an early Commons vote on whether to press ahead with plans to cut the number of MPs from 650 to 600.
The House is due to vote in the autumn on new parliamentary boundaries – based on rule changes introduced by the former coalition government in 2011 – reducing the number of constituencies.
However, the Commons Public Administration and Constitutional Affairs Committee warned it was unlikely to pass given the current state of opinion in the House.
If the measure was defeated, the committee said it would be too late to carry out a fresh boundary review in time for the 2022 general election, which would have to be fought on the existing boundaries based on population data more than 20 years out of date.
“If it moved quickly, it would be possible for the Government to introduce new legislation to allow for a new boundary review and for it to be implemented prior to a 2022 election. However, the window for such a decision is short,” the committee said.
“What is clear is that there are serious problems with using the existing boundaries for a further election in 2022, which appears to be the only likely alternative option given the parliamentary arithmetic.”
“They reflect neither the changes in population since 2000, nor how devolution has further affected the UK’s constitution, especially in respect to Wales.”
Committee chairman Bernard Jenkin said: “The time to decide this in principle is now. If the Government waits until the autumn, Parliament will be faced with an invidious choice: either approve the new boundaries or hold the next election on boundaries that will be over 20 years out of date.
“But, if we decide this now, it would be possible to change the law so new boundaries at 650 seats can be in place before the next election.”