President Obama on Monday sternly admonished the financial industry and lawmakers to accept his proposals to reshape financial regulation to protect the nation from a repeat of the excesses that drove Lehman Brothers into bankruptcy and wreaked havoc on the global economy last year.

But with the markets slowly healing, Mr. Obama’s plan to revamp financial rules faces a diminishing political imperative. Disenchantment by many Americans with big government, along with growing obstacles from financial industry lobbyists pressing Congress not to do anything drastic, have also helped to stall his proposals.

Mr. Obama chastised Wall Street denizens in the audience at Federal Hall, at the foot of Wall Street. “Instead of learning the lessons of Lehman and the crisis from which we are still recovering, they are choosing to ignore them,” Mr. Obama said. “They do so not just at their own peril, but at our nation’s.”

The speech came on the first anniversary of the collapse of Lehman Brothers and implicitly recognized that time was an enemy of reform. Throughout history, most major laws to change the financial system arose from the cauldron of a crisis. Senior officials have acknowledged that as the financial system begins to mend, a kind of political inertia sets in as lawmakers have less of an incentive to act boldly.