WASHINGTON — Senator McCain is promising to enter into new agreements with Russia aimed at reducing the two largest nuclear arsenals left on the planet and renegotiate the terms of the Nuclear Nonproliferation Treaty, the compact the United Nations Security Council has three times said Iran is violating in its continued enrichment of uranium.

The emphasis on arms control in an Arizona speech today marks a rhetorical departure for a candidate who has been tougher on Moscow on the campaign trail than either Senator Obama or President Bush. In March, for example, Mr. McCain proposed kicking the Russians out of the Group of Eight industrialized nations.

The speech was also a subtle jibe at the Bush administration for failing to change the NPT at an international conference in 2006 and for pursuing some weapons programs Mr. McCain said he opposes. This evening, Mr. McCain will attend a private fundraiser with Mr. Bush in Phoenix, Arizona.

Referencing President Reagan’s famous speech where he announced his “dream” that the world would be free of nuclear weapons, Mr. McCain said, “That is my dream, too. It is a distant and difficult goal. And we must proceed toward it prudently and pragmatically, and with a focused concern for our security and the security of allies who depend on us.”

Specifically, Mr. McCain said he would take up the Russians on their offer to negotiate an end to intermediate nuclear weapons that can be launched at a range of 500 to 550 kilometers.

On the NPT, Mr. McCain said if elected president, he would seek to change the terms of the treaty so as to punish any country, like North Korea and Iran, that illicitly sought fissile material without notifying the International Atomic Energy Agency.

“The IAEA shouldn’t have to play cat-and-mouse games to prove a country is in compliance,” he said. “It is for suspected violators to prove they are in compliance. We should establish a requirement by the UN Security Council that international transfers of sensitive nuclear technology must be disclosed in advance to an international authority such as the IAEA, and further require that undisclosed transfers be deemed illicit and subject to interdiction. Finally, to enforce treaty obligations, IAEA member states must be willing to impose sanctions on nations that seek to withdraw from it.”

Mr. McCain said as president he would consider changes to the Comprehensive Nuclear Test Ban Treaty, a treaty he opposed in 1999, that would make it more likely for the Senate to support it. The Arizona lawmaker also said he would seek to unilaterally reduce America’s nuclear arsenal. He singled out the Robust Nuclear Earth Penetrator, a program that has been opposed by Congress.

A spokesman for Senator Obama, Bill Burton said in response to the speech that Mr. McCain had stolen many of his candidate’s ideas.

“By embracing many aspects of Barack Obama’s nonproliferation agenda today, John McCain highlighted Obama’s leadership on nuclear weapons throughout this campaign, and his bipartisan work with Richard Lugar in the Senate. No speech by John McCain can change the fact that he has not led on non-proliferation issues when he had the chance in the Senate, and that his support for a war against Iraq – which had no active nuclear program – diverted us from our efforts to secure loose nuclear materials, hampered our ability to pressure countries like North Korea and Iran, and sets back our ability to lead the world against the threat of nuclear weapons,” he said.