La'aulialemalietoa Leuatea Schmidt was sacked from the ruling party by its executive last year, for crossing the floor in a vote in the House.
However, the MP refused to accept his removal, sitting in the party's backbenches for more than a year before announcing his resignation from the Human Rights Protection Party in May.
Last week, he offered his resignation from parliament while it debated a privileges committee report into his conduct.
That report said La'aulialemalietoa had misled parliament about a $US300,000 generator for the Tanumalala prison.
Prime Minister Tuila'epa Sa'ilele Malielegaoi said La'auli should prove he is a man of his word and actually resign.
The MP has recently stated he will start his own political party for next year's general election.
This followed confirmation that he could remain in parliament as an independent because he was sacked by his party. Had he resigned, the constitution requires a by-election.