Dumped premier Denis Napthine has spat the dummy and quit as Victorian Liberal leader, leaving the opposition leadership open for a battle between two of the party’s rising stars: Matthew Guy and Michael O’Brien. What do we need to know about the candidates vying for the chalice, poisoned or not, of opposition leader?

Matthew Guy, the former planning minister, is known for his active role in the development of Melbourne and some questionable interventions in property decisions across the state. For example, his rezoning of inner-city industrial suburb Fisherman’s Bend to be in the Capital City Zone instantly increased property values there and paved the way for high-rise development, which blindsided local Port Phillip Council.

His centralised use of planning powers has been a hallmark of his time in the job. Guy is the front runner in the party room ballot.

Former treasurer Michael O’Brien, who delivered two of the former government’s budgets, has also nominated for the leadership. O’Brien took over the job from Kim Wells, who was bumped off to police minister after the leadership spill of March 2013 that made Napthine premier.

Both candidates have been active on social media and traditional media throughout their stint in government, but their methods are a bit different. Guy deals with the media directly, calling journalists if he sees inaccuracies in their reporting.

Online, both candidates get a bit looser. Guy was active on Twitter in the lead-up to the election, hitting out at the Labor Party and taking aim at Labor’s links to the Construction, Forestry, Mining and Energy Union.

He also used his Twitter account to embarrass journalists with his criticisms, rather than discreetly asking for a correction.

O’Brien went silent just before the election, but in the lead-up he engaged in Twitter shaming, taking aim at regular punters rather than those in the political know.

Amy Feldtmann says she is a Kooyong resident and a swinging voter. Why then does O’Brien have a dig at her in this Twitter exchange on November 25, four days from the fatal poll?

Feldtmann, who works in communications, was accused of being “partisan, not principled”, but she was not cowed by the then-treasurer of Victoria and shot back that he was petty and foolish. These sort of sprays could hurt a future leader if not tamed; Feldtmann has repeated references to O’Brien’s outbursts elsewhere.

Apart from his forays into personal attacks on voters in safe Liberal seats, his engagement online has been directed mainly at political point scoring. One tweet Crikey can perhaps forgive him for is reposting the underappreciated hair-metal band Skid Row’s video for hard-rock ballad I Remember You. Perhaps there is more to O’Brien than meets the eye.