We all know the Howard model (if it even makes it to a referendum) will get rejected by the people. The speculation on why Howard is pushing it is fun. Speculating on why labor would support it is sad.
What's sadder is the vacuum the debate is happening in. The states have constitutions. New South Wales sends deadlocked bills to a referendum and empowers the legislative assembly to pass supply without consent of the legislative council. Victoria (roughly) follows the Howard model. Victoria treats supply bills the same way as NSW.
Victoria has also enacted a highly declaratory rule:
Section 16A. The principle of Government mandate
(1) It is the intention of the Parliament that regard should be given to the following principle--
The Council as a House of Review will exercise its powers in recognition of the right and obligation of the current Government to implement--
(a) the Government's specific mandate--the policies, promises and initiatives which were publicly released by or on behalf of the Government during the last election campaign; and
(b) the Government's general mandate--to govern for and on behalf of the people of Victoria.
(2) The principle in sub-section (1) is not to be construed as limiting the powers of the Council, the Assembly or the Parliament.".
Queensland, the ACT and the Northern Territory have taken the more drastic option of not having a second chamber. Why does federal constitutional debate always happen in a vacuum?