Less than three months after his inauguration, President Barack Obama stood before a cheering throng in Prague’s historic Hradcany Square and outlined an ambitious vision of a world without nuclear arms.

In remarks recalled later by the Nobel Peace Prize panel, Obama promised to negotiate a new strategic arms treaty with Russia, strengthen safeguards against the spread of nuclear weapons and engage Iran and North Korea to stop proliferation.

“I state clearly and with conviction America’s commitment to seek the peace and security of a world without nuclear weapons,” he said to applause.

“This goal will not be reached quickly - perhaps not in my lifetime. It will take patience and persistence.”

Three years later, as the president enters the final stretch of his re-election bid, Obama has yet to truly stamp U.S. nuclear policy with his own imprint, experts say.

The document that would define how deeply the United States is prepared to cut back its nuclear arsenal - perhaps to 1,000 warheads or less - and how radically to alter U.S. nuclear doctrine is still awaiting Obama’s final approval.

Like other unfinished business, from a federal budget deal to immigration reform, key nuclear weapons decisions apparently have been delayed until after the November 6 election. Arms control advocates fear they might never happen if Obama loses.

A White House spokesman declined comment on the status of the highly classified document, known as the Nuclear Posture Review implementation study.

Obama took office with a major focus on the perils of nuclear proliferation and scored early successes. But after a burst of energy that led to the New START treaty with Russia, measures to strengthen the Non-Proliferation Treaty and a new effort to secure nuclear materials worldwide, the administration’s push has flagged in the face of political realities and competing national interests.