A close associate of Putin and Russia's finance minister for most of the past decade, Mr. Kudrin is credited with the tough fiscal policies that enabled Russia to pay off its accumulated debts from the 1990s, run up big budget surpluses, and later ride out the global financial crisis of 2008. He threatened to quit last September after Putin announced he would seek a third presidential term and was dramatically fired by President Dmitry Medvedev. Kudrin has warned against a drift to "populism," including soaring military budgets and increases in pensions and industrial subsidies over the past year. On Dec. 24 he addressed the huge Moscow pro-democracy rally, where he warned the crowd against "revolution" and offered to act as a mediator between the protesters and the Kremlin. Kudrin has suggested he might form a liberal party to appeal to the aspirations of Russia's new middle class, who are heavily represented among the protesters so far.