Questions have been raised over the appointment of a new advisor to the Welsh Assembly's presiding officer.
Rhuanedd Richards will advise Plaid Cymru AM Elin Jones - who oversees assembly proceedings - having worked for the party for 10 years.
Welsh Conservative leader Andrew RT Davies questioned how they could work effectively across party lines.
The assembly commission said there was a "robust assessment" for the post.
The role is a public appointment, meaning Ms Richards is required to be politically neutral in the job.
Ms Richards was a special advisor to former deputy first minister and Plaid Cymru leader Ieuan Wyn Jones for four years.
She later spent five years as chief executive of the party and has recently worked as a lobbyist for Deryn Consulting.
Mr Davies said: "No-one could question Rhuanedd Richards' considerable political experience, but it was gained in pursuit of a narrow, partisan agenda - as chief executive of Plaid Cymru.
"It is scarcely conceivable to imagine a circumstance in which the general secretary of the Labour Party, or the chief executive of the Conservatives, would be considered an appropriate choice for the equivalent post with the speaker at Westminster.
"Both the presiding officer and her political advisor will have tricky waters to navigate, and they will have to work very hard to dispel questions over their ability to work effectively across traditional party lines."
A spokesman for the assembly commission, which is in charge of the institution's day-to-day running, said there had been a "full and open external recruitment campaign" to ensure the "best field of suitably qualified candidates".
"A robust assessment took place in line with all other assembly commission appointments," they added.
"The assembly's chief executive and the director of commission services independently assessed a good field of candidates and recommended a shortlist to the Llywydd [presiding officer].
"The interview panel, comprising the Llywydd and the initial assessors, interviewed individuals on 13 February after which an appointment was offered to the candidate whose evidenced demonstrated the most experience across the range of criteria required for the post."