KIEV, Ukraine — Vice President Joseph R. Biden Jr. urged Ukrainian leaders on Tuesday to curb the power of the business moguls dominating society and to fulfill the promise of the popular revolution that pushed out a pro-Moscow government last year.

Addressing the Ukrainian Parliament, Mr. Biden sternly lectured lawmakers to put aside their own self-interests and to transform this former Soviet republic into a model of democratic change.

Citing the failure of the Orange Revolution of 2004 to deliver enduring change, he urged Ukrainians not to let this opportunity slip by as well.

“This is your moment,” he told them. “This is your responsibility. Each of you — if you’ll forgive me for speaking to you this way in your body — each of you has an obligation to seize the opportunity that the sacrifices made in the Maidan, the sacrifices of the Heavenly Hundred. Each of you has an obligation to answer the call of history and finally build a united, democratic Ukrainian nation that can stand the test of time.”