Lord Strathclyde: 'Respect the will of the elected Chamber'
A referendum on the Westminster voting system is set to be held on 5 May.
Voters will be asked whether they want to replace the existing first-past-the-post system used to elect MPs in favour of the Alternative Vote system.
Legislation authorising a referendum received royal assent late on Wednesday night after a stand-off over the issue which saw MPs get their bill through Parliament.
Lords leader Lord Strathclyde had earlier urged a packed House to back down and "respect the will of the elected Chamber" over the issue.