WASHINGTON — The Obama administration plans to limit pay to $500,000 a year for executives of government-assisted financial institutions in a new get-tough approach to bankers and Wall Street, a senior administration official said Tuesday.

Obama plans to announce the new limits with Treasury Secretary Timothy Geithner at the White House today.

"If the taxpayers are helping you, then you've got certain responsibilities to not be living high on the hog," President Barack Obama said in an interview with "NBC Nightly News."

An administration official familiar with the new restrictions said the most restrictive limits would apply only to struggling large firms that receive "exceptional assistance" in the future. Healthy banks that receive government infusions of capital would have more leeway.

The official, speaking on the condition of anonymity because the plan had not yet been made public, said firms that want to pay executives above the $500,000 threshold would have to compensate them with stock that could not be sold or liquidated until they pay back the government funds.

The president and members of Congress have been weighing various proposals to restrict chief executives' compensation as one of the conditions of receiving help under the $700 billion financial bailout fund.

Banks and other financial institutions that receive capital infusions, but are considered healthy, could waive the $500,000 salary cap and the stock restrictions. But they would have to disclose the compensation and submit the pay plan to shareholders for a nonbinding vote.

The administration also will propose long-term compensation restrictions even for companies that don't receive government assistance, the official said.

The proposals include:

n Requiring top executives at financial institutions to hold stock for several years before they can cash-out.

• Requiring "say on pay" nonbinding shareholder resolutions.

• A Treasury sponsored conference on a long-term overhaul of executive compensation.

Top officials at companies that have received money from the government's Troubled Asset Relief Program already face some compensation limits. But elected officials want to place more caps, a sentiment reinforced in recent days by revelations that Wall Street firms paid more than $18 billion in bonuses in the midst of the economic downturn in 2008.

"I do know this: We can't just say, 'Please, please,"' said Sen. Claire McCaskill, D-Mo., who has proposed that no employee of an institution that receives money under the $700 billion federal bailout can receive more than $400,000 in total compensation until it pays the money back.

The figure is equivalent to the salary of the president of the United States.