In a wide-ranging speech at the London School of Economics he made the case for Wales’s continued membership of both the UK and the EU. The First Minister further outlined his position on the devolution of borrowing and taxation powers for the Welsh Government and his desire to move to a reserved model of devolution for Wales.
He called for the devolved legislatures to have the power to nominate potential members to the House of Lords and for a Welsh Judge to sit on the Supreme Court.
On a possible referendum on the UK future membership of the EU, he said:
"Imagine a referendum on the European Union which resulted in a vote to leave, carried by the weight of English votes against the preferences of other parts of the UK to remain in membership. That would put us under enormous strain, and could only serve the interests of those who wanted the United Kingdom to cease to exist.
"It is ironic that those who are pressing for an ‘In/Out’ referendum on the grounds of their commitment to the United Kingdom may actually be imperilling the very future of the UK as presently constituted. And that would be a matter of grave concern to the majority of people in Wales.
"Wales remaining part of the United Kingdom benefits our economy. The UK works for all of its constituent nations, and all have contributed to its success. I want the Union to flourish, and Wales to play a dynamic role in it. But for this to happen, the structures of the UK must adapt to the changing identities and aspirations of its citizens."
Addressing the topic of financial reform, the First Minister raised the prospect of tax devolution:
"For the devolution of any specific tax to be meaningful, there must be a realistic prospect of those tax-varying powers being exercised, which could mean different rates and thresholds operating on either side of the England-Wales border.
"The devolution of income tax is clearly feasible in principle, since it is in the process of being partly devolved to Scotland. But for both constitutional and practical reasons the situation in Wales is more complicated.
"Welsh voters would expect a say before they found themselves potentially paying a different rate of income tax than in other parts of the UK. In other words, there should be a referendum before this power could be transferred.
"The practical barriers to income tax devolution should not be minimised. The administrative challenge of operating two income tax regimes, for governments, businesses and citizens, would be significant. For those reasons, the Welsh Government has not sought income tax powers.
"There may be scope to move more swiftly to a model of income tax assignment – that is, where part of the Welsh Government’s resources are drawn from Welsh income tax receipts, but without devolution of any powers to vary income tax rates. Full devolution of rate-varying powers could follow at a later stage, with popular consent.
"I know that the Silk Commission is looking at income tax as part of its work. No doubt they will have given some thought to the practicalities of how devolution of the tax could be made to work. If they are able to provide reassurance on that score, and if we can be sure that the people of Wales have the opportunity to give their consent, then I would not object to looking at whether some responsibility for income tax could be included in a package of reforms."
On the reform of the House of Lords, he said:
"“I find it inexplicable that the recent proposals for House of Lords reform were developed entirely without regard to the UK’s territorial constitution. If we are to retain the system of appointment rather than election to membership of the House of Lords, I believe that the devolved legislatures should be entitled to make an agreed number of nominations of potential members."