The French opposition UMP Party says it wants to know how the new French Assembly member for Wallis and Futuna ended up siding with the ruling Socialist Party.
A senior parliamentarian, Christian Jacob, says he would like to find out how the Socialists managed to officially enlist Napole Polutele on their ranks when his campaign in March was funded by the UMP.
The UMP says this amounts to a poaching scandal.
Mr Polutele was elected in a by-election after the French Constitutional Court annulled last year's election result because the winner, David Verge, was found guilty of campaign irregularities.
Mr Verge was also banned from running for office for a year, prompting his wife to seek the seat, but she came only third.