Choose Cardiff Bay or Brussels, UKIP AMs tell Nathan Gill
UKIP Wales leader Nathan Gill is being urged to choose between being an MEP and an assembly member.
UKIP AM Dave Rowlands said it was the view of the party's assembly group that Mr Gill "shouldn't be doing both jobs".
Mr Rowlands said it was important for the "public perception" of the party.
A spokesman for Mr Gill said Wales needed an experienced MEP after the vote to leave the EU and someone new in the post would take time to "find their feet" in the European Parliament.
On Sunday Nathan Gill said he would continue as an MEP because it had become a "non-position" following the UK's vote to leave the EU.
In a leaflet sent to members during his party's assembly selection process in February, Nathan Gill said he would "resign as an MEP" to work in the assembly.
But speaking over the weekend on Sunday Supplement on BBC Radio Wales Mr Gill said: "I will be keeping the MEP position because it's now become a completely non-position.
"I don't get paid for that position, I get 300 Euros a week for being an MEP.
"So it doesn't make any real difference, financial sense for changing that position with somebody else.
"My focus now will be on the assembly."
Dave Rowlands, AM for South Wales East, said: "The belief among UKIP AMs is he shouldn't be doing both jobs and he must make a choice between the two jobs.
"It's very important regarding the public perception of the party.
"Grassroots are reported to be showing great disquiet about this issue."
Another UKIP AM, Gareth Bennett, said Gill should resign as an MEP in order to "do a satisfactory job in the assembly, which he has thus far signally failed to do."
His colleague Michelle Brown said being an AM "is a full-time job" and she questioned Mr Gill's ability to do it.
Speaking in a personal capacity, Tony Roper, UKIP Swansea branch chair said: "I'm not happy about Nathan Gill doing two jobs.
"I would like to know how much time Nathan is spending in Wales.
"He should keep his promise."
A spokesman for Mr Gill responded: "With the country deciding to leave the EU it is important at this time we have an experienced member of the European Parliament representing Wales.
"For any MEP it would take time to find their feet with the institution and time is something we haven't got at this point.
"Nathan has spoken with senior party officials on UKIP NEC and in [the] leadership who advised him to stay on to insure the strongest team possible fighting for UK and Wales and the best possible outcome post-Brexit."
The spokesman also stressed that "Nathan does not receive two salaries".