WASHINGTON - US President Barack Obama, in a populist step designed to appeal to voters, will propose a "Buffett Tax" on people making more than $1 million a year as part of his deficit recommendations to Congress on Monday.

Such a proposal, among suggestions to a congressional supercommittee expected to seek up to $3 trillion in deficit savings over 10 years, would appeal to his Democratic base ahead of the 2012 election but may not raise much in revenues.

White House Communications Director Dan Pfeiffer said on Saturday the tax would act as "a kind of AMT" (Alternative Minimum Tax) aimed at ensuring millionaires pay a minimum rate of tax that at least matches that of middle-class families.