If NSW Premier Morris Iemma is fair dinkum about restoring some credibility and cohesion to his dysfunctional government, then tomorrow’s Cabinet reshuffle is a no-brainer — he will sack his Treasurer Michael Costa who has been the chief architect of the administration’s political misfortunes.

Costa bears almost sole responsibility for driving out Deputy Premier, Transport Minister and Finance Minister John Watkins who resigned yesterday pleading “physical and emotional strain” — a medical term for being in the same room too often with Costa.

The Daily Telegraph’s Simon Benson delivered the best line saying that Watkins’ departure was like a ship leaving sinking rats.

Another act of political sanity would be to slot former Sydney Lord Mayor Frank Sartor into Costa’s job at Treasury and underscore the fact that Sartor successfully hosted the $2 billion Olympic Games in 2000.

And to finish the makeover Iemma should bring back Carmel Tubbutt as deputy premier and restore her to the education portfolio which she handled with considerable skill prior to the March 2007 state election.

Tebbutt and fellow left-winger Julia Gillard, the Federal Education Minister, would make a formidable duo in reshaping education and redressing the funding shortages to public education.

Primary Industries Minister Ian Macdonald, recently dumped from the leadership of the left because of his arrogant promotion of electricity privatization, is to take the critical planning portfolio which is now the “crown jewels” of the Cabinet.

Police Minister David Campbell, the former mayor of Wollongong, is likely to replace Watkins as transport minister while Cabinet up-and-comer Nathan Rees has been tipped for primary industries.

Cleared of any charges arising from misbehaviour at Iguana’s waterfront restaurant at Gosford on June 6, suspended John Della Bosca will come in from the cold to take the heat at health, the “poisoned chalice” portfolio. He’s even been on a healthy weight loss course to take the job and has shed kilos while cycling and walking since losing his driver’s licence for speeding.

The big losers will be “Grim” Reba Meagher who will be dumped as Health Minister and Graham West, the Minister for Gaming and Racing and Sport, while fortune will smile on David Borger, the former mayor of Parramatta, who is due for a ministry after loyally backing privatization.

Can the re-arrangement of the deck chairs on the deck of the SS Iemma save it from taking more water and sinking? Unlikely, because the damage to the hull, the engine room and the bridge has been devastating. It is listing and so is the captain.

The chief beneficiary of Labor’s implosion is, of course, Barry O’Farrell’s Opposition. If the Liberals choose a half-decent candidate, they can win Watkins’ seat of Ryde at the by-election next month.

In this incendiary political climate, even Watkins’ 10 per cent margin will not stop the enraged middle class of Sydney’s upper north shore taking the baseball bats and hockey sticks to Labor and returning the seat to the Liberals for the first time since 1995.

The Ryde by-election is likely to be held on October 18, the same day Port Macquarie voters go to the polls to find a successor to their Independent MP, Robert Oakeshott, who is heading to Canberra if he wins Saturday’s vote in Mark Vaile’s old seat of Lyne.

The Nationals have chosen registered nurse and former teacher Leslie Williams, a widely admired and well respected community activist, as their candidate and she should win.

If the Coalition wins both by-elections, with one extra seat for the Liberals and another for the Nationals, O’Farrell’s advance on the premiership at the state election in March 2011 will suddenly became a whole lot more feasible.