The First Ministers of Scotland and Wales have written to peers setting their own proposed changes to crucial Brexit legislation.
The Scottish and Welsh governments have been locked in a dispute with the UK Government over the return of devolved powers from Brussels once Britain leaves the EU.
While UK ministers have brought forward amendments to the EU (Withdrawal) Bill aimed at addressing the disagreement, Nicola Sturgeon and Carwyn Jones said they did not have their support.
The leaders have written to the House of Lords ahead of its consideration of aspects of the bill related to devolution on Monday.
UK ministers want to retain temporary control in areas such as agriculture, fisheries, food labelling and public procurement after Brexit.
They say a "temporary restriction" on the devolved governments using some of the powers returning from the EU is "to help ensure an orderly departure from EU law" and allow common frameworks to be established.
In their letter, the First Ministers said their governments agreed common frameworks are appropriate in some cases, however they said UK ministers' amendments would see them only "merely consulted" on these.
They have called for further amendments to ensure that the temporary restriction on devolved powers would require their consent, and any primary legislation required to establish common frameworks must be agreed by them.
They have also called for a "sunset clause" on the restrictions.
While talks between the devolved administrations and the UK Government continue, the leaders stated that they "would be pleased to put forward detailed amendments if it proves impossible to reach agreement".
"The two governments have also asked that the UK Government agree a level playing field and make a commitment not to bring forward legislation in respect of England in those areas where it is agreed common frameworks are to be established," they added.
The letter to the Lords follows a meeting between the First Ministers and Theresa May earlier this week.
Speaking afterwards, Ms Sturgeon said the "issues that remain between us are not insignificant but
neither are they insurmountable", while Mr Jones said he was "hopeful" of an agreement.