The speaker of Australia's Parliament has resigned, weakening the government's tenuous grip on power.

Prime Minister Julia Gillard's center-left Labor Party government recruited Peter Slipper from opposition ranks to the speaker's post last year in a move that effectively gave her administration a two-seat majority on most votes in the House of Representatives.

Because a speaker can only vote to break a tie, Slipper's promotion freed up his predecessor's vote for Labor.

Since then, an independent lawmaker has withdrawn his support for the government.

Slipper resigned on Tuesday over fallout from a sexual harassment lawsuit against him.

With Labor lawmaker Anna Burke elected to replace him, Gillard has now become reliant on Slipper as an independent lawmaker to pass her legislative agenda.