WASHINGTON - US President George W. Bush flew to Europe on Monday with his popularity at home at a low point over the Iraq war and tensions abroad over global warming and missile defense.

Built around the Group of Eight summit in Germany where his host, Chancellor Angela Merkel, had hoped to forge an agreement on climate change, Bush's trip includes stops in Eastern Europe to bolster developing democracies.

With many Americans clamoring for an end to the Iraq war, the Republican president focused on a softer agenda before the meeting.

Laying out his goals last week, Bush asked Congress to double funds for combating AIDS, primarily in Africa, to $30 billion over five years and tried to dispel criticism by proposing a new global warming strategy. He also slapped sanctions on Sudan for what he called the genocide in Darfur.

"If you couple Bush's weak position at home with this unpopularity in much of Western Europe, Bush is probably not relishing this trip," said Charles Kupchan, director of Europe Studies at the Council on Foreign Relations.

"Particularly on the question of climate change, he will find himself isolated."

Europeans gave a cool reception to Bush's plan to bring together the world's biggest polluting countries by year-end to explore ways of limiting emissions and agree on a long-term goal by the end of 2008.

Some portrayed it as a defeat for Merkel, who wants the G8 to agree now on a need for cutting emissions of greenhouse gases about 50 percent by 2050.

But Stephen Hadley, Bush's national security adviser, told reporters on the president's plane: "This is not about upstaging Angela Merkel. Quite the contrary ... It is an effort to identify a way forward."

Kupchan said the general view in Europe is, "Let's be patient, November 2008 is coming," referring to the next US presidential election that will herald the end of Bush's term.

The weeklong tour, with stops in the Czech Republic, Poland, Italy, Albania and Bulgaria, includes several firsts. Bush will meet new French President Nicolas Sarkozy in Germany and Pope Benedict at the Vatican.

Meeting with Putin

One of Bush's most closely watched meetings during the summit will be with Russian President Vladimir Putin, whose escalating criticism of the United States has raised concerns about the deterioration of US-Russian ties.

Putin warned that Russia would go back to its Cold War stance of aiming missiles at Europe if Washington pursued its plan for a missile defense shield near Russia's borders. Hadley said Putin's comments were "not helpful" and that the United States wanted a constructive dialogue with Russia.

Putin sees the missile shield as a threat to Russia. Washington insists it is intended to protect against potential threats from other states such as Iran and North Korea.

In a preemptive move that could take some of the tension out of the session, Bush has invited Putin to his family's retreat in Maine next month for two days of talks.

In Prague on Tuesday, Bush will address an international conference of human rights and democracy activists.

Hadley said Bush would speak about the "challenge of promoting democracy" in countries such as Russia and China. US officials have accused Putin of backsliding on reforms and have also pressed China for increased democratic freedoms.

His visit to Albania comes amid US-Russian disagreement over statehood for Kosovo, which is majority ethnic Albanian. Washington backs a UN proposal for Kosovo independence under international supervision. Russia opposes it.