Sir Gavin Williamson will table an amendment to Labour’s bill to block hereditary peers that would see all bishops kicked out of the House of Lords.
The former Conservative chief whip will make the case that Iran is the only other parliament in the world that reserves space for the clergy.
The Tory MP – who is expecting to get cross-party support for the change – said that it was wrong that he as an Anglican had greater representation than his Catholic children.
He will urge Labour to meet its manifesto commitment to bring about significant reform to the Parliament’s upper chamber, which they have watered down.
Should Sir Gavin’s amendment be selected, Labour MPs will have to vote it down – a vote in favour of the bishops – which will be uncomfortable for many who want Lords reform to go further and the party to honour its manifesto commitments.
Sir Gavin said: ‘Labour promised significant reform of the House of Lords, but they are not doing that.
‘This is an opportunity to make the House of Lords more reflective of today’s modern world, but also to make sure it is better run.
‘Instead of breaking another manifesto promise, the Government should use this as an opportunity to make change.
‘It’s ridiculous that the only other major country in the world that has clergy in the legislature is Iran.
‘Isn’t it about time to wake up to the reality that this requires reform?’
There are 26 ‘Lords spiritual’ – as the Church of England bishops and archbishops are known – in the House of Lords.
They include Justin Welby, the Archbishop of Canterbury, Stephen Cottrell, the Archbishop of York, and the bishops of London, Durham and Winchester.
All bishops are required to retire at the age of 70 when they are replaced by a female bishop. There are now six female bishops in the Lords.
Sir Gavin said Labour should stick to its manifesto commitment to reform the upper House and said he would table an amendment to scrap seats for bishops.
Less than 2 per cent of the British population attend Anglican services on a Sunday and more people selected ‘no religion’ than Christian in the 2021 census, he said.
He also noted that during the 2022-23 parliamentary session, the bishops took part in 6 per cent of divisions, compared with an average of 45 per cent for all members.
During the same period, they asked 204 oral questions out of a total of 7,641 across the House of Lords.
The last Labour government removed most hereditary peers from the Lords in 1999 but allowed 92 to remain in a short-term compromise to get the legislation through.
Sir Keir Starmer’s manifesto described the existence of peers who inherited their titles from their parents as ‘indefensible’.
It also said that Labour would introduce a mandatory retirement age of 80 and committed to transforming the House of Lords into a second chamber that is ‘more representative of the regions and nations’.
But there are no plans to introduce these changes at present.