WASHINGTON - President Bush may have liked what he saw when he first peered into Vladimir V. Putin's soul nearly six years ago. Yet while Bush was looking away, the sunnier horizon he sought with Russia turned cloudy.

Testy, suspicious, and defined by misunderstandings and perceived hurts, the relationship between the Cold War powers has worsened steadily on Bush's watch.

A worried Bush is sending Secretary of State Condoleezza Rice for fence-mending with Moscow this week, just three weeks after a similar mission by Defense Secretary Robert Gates.

Bush also called Putin on Thursday. The two leaders are to meet next month in Germany, and Washington is trying to prevent a diplomatic disaster.

Putin is not sounding receptive to the Bush administration's message that the United States intends no harm to an increasingly restive Russia. On Wednesday, Putin made what many took as a veiled comparison between the global aspirations of the United States and Nazi Germany.

U.S. officials point to numerous areas of cooperation with Russia, and insist that even a missile-tipped argument over U.S. defense plans in Europe does not signal the dawn of a new Cold War.

"On many things, we have done very well, but the fact is that, on some others, it's been a difficult period," Rice said in Senate testimony Thursday. Rice said the relationship was complicated by a rollback in democratic reforms in Russia and the Putin government's treatment of nearby states.

"Pretty rocky" was the harsher assessment of Steven Pifer, a specialist on Russia and former Soviet states at the Center for Strategic and International Studies.

It was not supposed to be this way, not with two leaders who seem to like one another, generally good economic times in both countries, and converging interests in the fight against terrorism. Rice, Bush's longtime top foreign-affairs adviser, is even a specialist on Russia and a fluent Russian speaker.

"I am sure that she is disappointed - everybody on a senior level in the State Department is disappointed," said Soviet-born Dimitri Simes, president of the Nixon Center in Washington. "They have every right to be disappointed. I am quite disappointed myself."

Perhaps Rice, of all people, should have seen the deterioration coming. But she, like the rest of the administration, became preoccupied with terrorism after the Sept. 11 attacks and with the wars in Afghanistan and Iraq that followed.

The chumminess between Bush and Putin was regarded as a foreign-policy bright spot, but the underlying relationship between the two countries was a relatively low priority.

"With everything going on in Iraq, with Iran, North Korea, at that level at some point you run out of time," Pifer said. "It's a question of bandwidth."

Russia and the United States talk past each other on the basic issues that divide them.

American officials look at Putin's consolidation of power, and see a dangerous retrenchment on basic democratic principles. Russia tunes out the lecture from a world power it considers overbearing and hypocritical.

The United States is unnerved by Russia's growing energy wealth, its use of energy as a political cudgel, and centralization of the once-entrepreneurial energy sector. Russian leaders see it as their return ticket to world relevance.

On Saturday, the leaders of Russia, Turkmenistan and Kazakstan reached a landmark pipeline deal that will strengthen Moscow's control over Central Asia's energy-export routes. The agreement sets back U.S. and European efforts to secure alternatives to Middle East oil and gas that would be independent from Russian influence.

The United States sees its plan to station missiles and interceptors at bases in Poland and the Czech Republic as a strategic bulwark against a potential threat from Iran, especially if Iran gains nuclear weapons. Russia sees the breaking of promises it thought it had exacted from the West and unacceptable U.S. encroachment on its doorstep.

As Putin enters what is probably the last year of his presidency, he has become more defiant of international pressure and more willing to challenge the West.

"President Putin thinks the United States has been weakened by Iraq and that he has been strengthened by recent events and high-priced oil," former U.N. Ambassador Richard Holbrooke said. "He is trying to put Russia back on the international map."