Former federal treasurer Peter Costello and several of the Liberal Party's most senior backroom players have emerged as key figures with interests in political lobbying in Victoria.

Mr Costello's ECG Advisory Solutions is one of several Liberal-leaning specialist business and strategic communications groups that have appeared on the Victorian register of lobbyists after the Baillieu government's victory.

The business is run by former senior ministerial advisers Jonathan Epstein and David Gazard, who worked for Mr Costello in the Howard Government.

Mr Costello is an investor and chairman of the ECG Advisory board and was the most senior Victorian Liberal until the 2007 federal loss.

The Baillieu government's victory a year ago has transformed the lobbying landscape, prompting Greens MP Greg Barber to call for greater scrutiny and tougher powers to keep MPs in check.

Mr Barber said the number of registered lobbyists was up from 204 last year to 256 this year.

Other Liberals to declare their interests as lobbyists include former Howard advisers Grahame Morris and John Griffin - who work for the firm Barton Deakin - and former state MP Geoff Leigh.

Mr Leigh is a controversial former Liberal MP turned fundraiser and "mentor" to Liberal candidates.

Former ALP national secretary Karl Bitar is the standout Labor lobbyist, acting for Crown Ltd, and has been active opposing proposed federal poker machine changes.

Labor's loss of the last state election has splintered the PR and lobbying scene in Victoria, and there is a growing trend by firms to have staff with both Labor and Liberal backgrounds.

Rick Brown, a former adviser to senior federal Coalition frontbenchers, has teamed with former Victorian ALP state secretary Stephen Newnham to run CPI Strategic.

Former state Labor cabinet minister David White's career in business was often controversial and he is no longer listed on the register as a lobbyist of Labor-leaning Hawker Britton. But records show he still has an interest in Hawker Britton.

The register was introduced in 2009 to keep track of who is lobbying whom to prevent a conflict of interest arising from within government.

Victorian Premier Ted Baillieu this week released his fundraising code of conduct for MPs. The code, which sets out major changes to the way MPs can raise funds, includes the terms under which money is accepted from companies and individuals.