A Liberal Democrat MEP for Yorkshire and the Humber is facing criticism after announcing her resignation, to be replaced by her husband without a vote.
Diana Wallis's husband, Stewart Arnold, is expected to take over his wife's seat in February.
Mr Arnold was placed second on the Lib Dems' candidates list in Yorkshire and the Humber at the last European elections.
UK Independence Party MEP Godfrey Bloom described the move as "nepotism".
In a statement, Ms Wallis, who has been an MEP for Yorkshire and the Humber for 12 years, said it had been "a truly huge privilege" to serve in the European Parliament.
However, she added that "all of us, whatever our professions, need to turn a new page from time to time".
Ms Wallis failed in a bid on Tuesday to become president of the European Parliament, standing as an independent candidate.
After losing out to German Socialist Martin Schulz, she said it was "a good time to take stock".
Ms Wallis added that her bid for the presidency had been "for reasons that I deeply believe in".
She will remain a Member of the European Parliament until 31 January, at which time Mr Arnold is expected to take over his wife's seat.
According to procedures, if a sitting MEP gives up his or her seat for any reason then the next candidate on a list previously chosen by their party is automatically elected to that seat.
'Taking the huff'
But Godfrey Bloom, a UK Independence Party MEP for Yorkshire and the Humber, said Ms Wallis's husband taking the role was "a working definition of nepotism".
Ms Wallis was "taking the huff" by resigning her seat, he added.
"The Lib Dems are always screaming in favour of gender quotas but Diane Wallis has gone all quiet about that now.
"Jobs for the boys now. You could hardly make this story up."
Former Europe minister and Rotherham Independent MP Denis MacShane said: "By any standard of nepotism it is unacceptable that as one Lib Dem MEP flounces out of the European Parliament because she failed in an ego trip bid to elected president of the European Parliament she is replaced by her own husband.
"His and hers seats for lucrative MEP slots make a mockery of Yorkshire's right to elect an MEP of their own choice."
Mr MacShane called on Lib Dem leader and Deputy Prime Minister Nick Clegg to "clear up this mess".