Could one of UKIP's new AMs become an MEP?
One of the big stories of election night was UKIP's entry into the Welsh assembly - with the success of seven of the party's candidates.
At the top of the North Wales UKIP list, and one of the new AMs elected, was Welsh leader Nathan Gill, who is currently a member of the European Parliament.
But a vacancy is set to appear after Mr Gill made it clear he wants to stand down from the European role - with suggestions he'll resign after the referendum.
And because of the rules that govern MEPs, his replacement could be one of the other UKIP members elected as AMs.
And if they do not want to head to Brussels, a by-election could be on the cards.
What's the process?
If an MEP resigns, a whole set of regulations kick in to find a replacement.
For the European elections, parties submit lists of names. UKIP got one Welsh MEP in May 2014 and so the number one on the list, Mr Gill, was elected.
Under the rules, the returning officer for the Wales region - currently the chief executive of Pembrokeshire council - would need to get in touch with the second person on the list and ask if they want to take up the position.
If that person cannot or does not want to do it, they can go to number three on the list and offer the position to them.
It is similar to what happens in the assembly if a sitting regional AM stands down - the next on the party list gets first refusal on whether they would like to take up the vacant post.
Who is on the UKIP list?
UKIP put forward four people for the 2014 European election when Nathan Gill was elected.
The first person that the returning officer could go to is James Cole, but he has left the party.
That would leave the choice to the third person on the list - Caroline Jones.
If she did not want the position, it could then be left to David Rowlands, 2014's UKIP number four.
Both were elected as AMs on 6 May. There appear to be no rules stopping an assembly member from being an MEP, but practicalities of travel may make it unrealistic and appear to be part of why Mr Gill has decided he does not want to do it.
It is unclear whether either Mr Rowlands or Ms Jones wants the role. If either took it up, and decided to leave the assembly, the process by which regional list AMs are replaced would then come into play.
Susan Boucher was next on the list for South Wales East after Mr Rowlands, while Martyn Ford followed Ms Jones in South Wales West.
A senior UKIP source said: "We've got a list of two people - one of those two is going to have to decide whether they would go to Brussels or stay."
"I imagine one of those two would take it."
Could there be a by-election?
If the process of trying to fill the vacancy by asking the remaining list candidates if they want the job fails, the UK government could call a by-election for the role.
Pembrokeshire council, which handled the European election in 2014, said UKIP only submitted four names for the poll, the maximum parties were allowed to submit.
But the senior UKIP source said that, although confident the party might win such a poll, it would not want that expense placed on the public purse.