Wrth i'r trafodaethau fynd ymlaen i'r cam hanfodol nesaf, rwyf wedi ysgrifennu ar y cyd ag Ysgrifennydd y Cabinet dros y Cyfansoddiad, Ewrop a Materion Allanol yn Llywodraeth yr Alban at Ganghellor Dugiaeth Caerhirfryn yn gofyn i Lywodraeth y DU wneud llawer mwy i weithio gyda'r Llywodraethau Datganoledig. Unwaith eto, rydym yn galw ar i Lywodraeth y DU gadw at gylch gorchwyl Cyd-bwyllgor y Gweinidogion (Negodiadau'r UE) sy'n ymrwymo pob un o'n Llywodraethau i gydweithio i gytuno ar safbwynt a rennir ledled y DU ar gyfer y negodiadau ac i sicrhau bod y negodiadau yn arwain at ganlyniadau y cytunwyd arnynt. Dim ond drwy weithio ar y cyd â'r Llywodraethau Datganoledig y gall Llywodraeth y DU sicrhau'r EU bod modd i'r berthynas y cytunir arni at y dyfodol gael ei rhoi ar waith ym mhob rhan o'r DU.
As the talks enter the next critical phase I have written jointly with the Cabinet Secretary for the Constitution, Europe and External Affairs in the Scottish Government to the Chancellor of the Duchy of Lancaster calling for a redoubling of efforts by the UK Government to work with the Devolved Governments. We once again call for the UK Government to honour the terms of reference of the Joint Ministerial Committee (EU Negotiations) which commits all our Governments to work together to agree a UK approach to the negotiations and to ensure that agreed outcomes are secured from the negotiations. It is only by working in collaboration with the Devolved Governments that the UK Government can provide the reassurances to the EU that the future relationship agreed can be implemented across all parts of the UK.