President Bush and British Prime Minister Tony Blair agreed to consider how to deal with security threats posed by the spread of dangerous weapons in the post-Cold War world.

Bush said he appreciates that Blair, unlike other leaders, is willing to consider new approaches to defense. Blair, who like most European leaders has been cool to the proposed U.S. anti-missile system, said Bush had taken the right approach by consulting with allies and recognizing the security threat posed by nations such as North Korea, Iraq and other so-called rogue nations.

Looking ahead to differences likely to emerge at an eight-nation summit in Italy this weekend, Bush said, "I look forward to a frank discussion in Genoa, and I'm confident we'll find areas to work together on and when we disagree, we'll do so in a respectful way." The two leaders met at Chequers, Blair's country estate.

Bush pledged to stay in touch with the prime minister as debate unfolds over the missile defense plan and Bush's desire to move away from a long-standing treaty that restricts developing such systems.

Blair noted that he is awaiting a specific missile defense proposal from the United States. Bush praised Blair for giving his idea a fair hearing. "It's hard for any country to commit to vague notions," Bush said.

On global warming, the two leaders alluded to differences but chose not to dwell on them. Bush said their nations share a goal of reducing greenhouse gases, and the United States wants to ensure that any solution does not hurt the U.S. economy.

"Our strategy must make sure that working people in America aren't going out of work," Bush said. "My job is to represent my country, and I'm going to do so in a way that keeps in mind the ability for people to find work and for our nation to be prosperous. I think economic growth and sound environmental policy can go hand in hand."

The two leaders spoke at a news conference a day after Bush arrived in London to open a six-day European trip, his second in a month.

Earlier in the day, the White House quickly and sharply disputed criticisms of the administration's foreign policy levied by Senate Majority Leader Tom Daschle.

Mr. Bush personally took exception to the timing of Sen. Daschle's criticism, since it is longstanding practice not to attack a president's foreign policy while he is abroad.

"One of the things America prides itself on is a bipartisan foreign policy," the President said.  "And I would hope that tradition would continue.  It's a very important tradition." 

Sen. Daschle told USA Today that the administration suffers from "fragile" relations with U.S. allies and that "we're isolating ourselves."

The United States currently has differences with some of its allies, such as Germany and France, over the president's efforts to proceed with missile defense and his opposition to the Kyoto treaty on global climate change that would place major restrictions on U.S. energy usage.

But White House counselor Karen Hughes called Sen. Daschle's comments an unseemly departure from standard practice.

"I don't know whether to chalk this up to the fact that the majority leader is still adjusting to his new role as majority leader," Hughes said. "But this sort of thing is simply not done."

Even though he said he sat for the interview while Bush was still in town, Daschle stood by them on Thursday while Bush was in London in the early stages of a weeklong European trip.

"Had I given some thought to the fact that the president was departing, I probably would have chosen a different time to make those comments," Daschle told reporters in his Senate office. "But having said that, I certainly will not back away."

Rep. Christopher Cox, R-Calif., chairman of the GOP House Policy Committee, suggested that Daschle's comments were contradictory on their face. "It's at least customary to notice that the president is in Europe when one says that he's isolating America," Cox said.

Politicians of both parties are fond of quoting the late Sen. Arthur H. Vandenberg, a Michigan Republican who 50 years ago wrote the script for World War II bipartisanship in foreign policy.

Vandenberg urged colleagues "to unite our official voice at the water's edge so that America speaks with maximum authority against those who would divide and conquer us."

But that old adage has been breached often, and by both parties.

Some Republicans had little hesitation in criticizing former President Clinton, a Democrat, regardless of whether he was at home or abroad.

For instance, House Majority Whip Tom Delay, R-Texas, suggested while Clinton was traveling in the Middle East in late 1998 that the impeachment scandal had destroyed his international credibility. "Saddam Hussein knows it, and that's why he jerks his chain all the time," DeLay said.

Daschle cited such examples in defending his comments. "I did think that it's unfortunate that on so many occasions during the Clinton administration, Republicans were extraordinarily critical and damaging to the president's efforts when he attempted a number of foreign policy initiatives."

Fox News' Jim Angle and The Associated Press contributed to this report