"It's a tough time and its a difficult moment for America and Great Britain and the task before us is daunting," Bush said a day after a bipartisan commission said his war policies have failed and called for a change in strategy.
The British prime minister, who has stood shoulder to shoulder with Bush since the March 2003 invasion of Iraq, said he welcomed the conclusions of the Iraq Study Group despite its criticism of past policies.
It "offers a strong way forward," Blair said. He said "the consequences of failure are severe."
Bush appeared to endorse the panel's conclusion that any resolution of the Iraq conflict is tied to reducing tensions between Israel and the Palestinians and across the broader Middle Easta position Blair has long held.
But in Tel Aviv, Israeli Prime Minister Ehud Olmert said he disagreed with the advisory group's linkage. He told a news conference that conditions were not ripe to reopen long-dormant talks with Syria.
"I appreciate your clear view that we are confronted with a struggle between moderation and extremism and this is particularly evident in the broader Middle East," Bush told Blair.
Both Bush and Blair said that supporting the government of Iraqi Prime Minister Nouri al-Maliki was central to efforts to help Iraq defend, govern and sustain itself.
"The American people expect us to come up with a new strategy," Bush said.
"I believe we need a new approach and that's why I've tasked the Pentagon to analyze the way forward," he said. In addition to the Iraq Study Group, studies are under way at the Pentagon, State Department and National Security Council on next steps.
The response made it clear that Bush did not intend to be influenced only by the bipartisan panel's report, which contained 79 specific recommendations, but by the other studies as well.
One of the study group's central recommendations was for the administration to reach out to Syria and Iran for help in stabilizing Iraq, a course Bush has rejected in the past.
"Countries that participate in talks must not fund terrorism, must help the young democracy survive, must help with the economics of the country," Bush said. "If people are not committed, if Syria and Iran is not committed to that concept, then they shouldn't bother to show up."
For his part, Blair suggested that Iran's support for Shiite militants in southern Iraq presented a problem. "Iran has been...basically arming, supporting, financing terrorism," the visiting British leader said.
Blair said the terrorists' threat in Iraq is part of an old pattern that is region-wide. Terrorism "has basically come out of the Middle East" and must be addressed in a way that includes a solution to the Palestinian-Israeli conflict, he said.
"It's bad in Iraq," Bush said. "I've been telling the American people how tough it is and they understand how tough it is. The question is, 'Do we have the ability to change as the enemy has changed?' "