As John Kerry (search) on Monday challenged President Bush's (search) execution of the War on Terror and the administration's Iraq policy, the Republican incumbent delivered a new speech aimed at gaining an edge on the neck-and-neck race for the White House.

"As president, I will always work with other countries. I will seek their advice. But there's a world of difference between working with good allies and giving a few reluctant nations veto power over our national security," Bush told a crowd in Greeley, Colo.

"I will never, never submit our national security decisions to veto of a foreign government," Bush added.

Bush again took aim at a comment Kerry made during the presidential debates, where he said he would make sure, if elected, that America passed a "global test" before making any moves in the War on Terror.

"In addition to a global test, my opponent promises what he calls a golden age of diplomacy to charm political governments all over the world. I don't see much diplomatic skill in Senator Kerry's habit of insulting America's closest friends," Bush said. "He has called the countries serving alongside us in Iraq, quote, 'a trumped up coalition of the bribed, the coerced, the bought and the extorted.'"

White House Communications Director Dan Bartlett said Bush would be using some new language in his speeches during the final weeks of campaigning, beginning with the Greeley rally. The president headed to Iowa afterward for events in Council Bluffs and Davenport.

On the trail Monday in Dover, N.H., and Philadelphia, Kerry described the discovery that 380 tons of explosives had gone missing from an Iraqi military base as "one of the great blunders" of the war.

"Terrorists could use this material to kill our troops, our people, blow up airplanes and level buildings," Kerry said. "The unbelievable blindness, stubbornness, arrogance of this administration to do the basics have now allowed this president to once again fail the test of being the commander in chief."

Bush shot back quickly.

"My opponent has the wrong strategy for the wrong country at the wrong time," the president said at a campaign stop.

Former President Bill Clinton (search ), still recovering from heart surgery seven weeks ago, joined Kerry at a rally in Philadelphia on Monday, then traveled to Florida in the evening. The Kerry camp hopes Clinton will help increase voter turnout in crucial Pennsylvania. The Philadelphia fire commissioner estimated that upwards of 100,000 people came out to see Clinton and Kerry.

"From time to time, I have been called the 'comeback kid' — in eight days, John Kerry's gonna make America the comeback country," Clinton told a rousing crowd in the City of Brotherly Love.

Kerry said the Bush administration had "miscalculated about how to go to war, miscalculated about the numbers of troops that we would need, miscalculated about sending young Americans to war without the armor they needed, without the Humvees they needed that were armored."

"And the incredible incompetence of this president and this administration has put our troops at risk and put this country at greater risk than we ought to be," he added.

Mystery of the Lost Explosives

The International Atomic Energy Agency (search) said about 380 tons of highly explosive material had disappeared in Iraq, apparently stolen because of a lack of security at governmental installations.

At the Pentagon, an official who monitors developments in Iraq said U.S.-led coalition troops had searched the Al Qaqaa (search) military base in the immediate aftermath of the March 2003 invasion and confirmed that the explosives were intact. Afterward, the site was not secured by U.S. forces, the official said.

Bush spokesman Scott McClellan played down the threat. He said the administration's first concern was whether the weapons missing from Al Qaqaa posed a nuclear-proliferation threat, and he said they did not.

"We have destroyed more than 243,000 munitions," he said. "We've secured another nearly 163,000 that will be destroyed."

Senior Defense officials pointed out that Iraq is "awash" in conventional weapons both large and small, and that latest estimates indicate that some 243,045 tons of such weapons have been located and destroyed since the invasion, while 162,899 tons are under guard and await destruction.

Weapons and explosives were hidden in mosques and schools, and were also buried in yards, the officials told FOX News.

The officials said that they were looking into the IAEA assessment and that the Iraq Survey Group (search), the CIA-led team searching for weapons of mass destruction, was taking the lead in determining where the explosives might have gone.

The Pentagon was said to be working on a further response to the IAEA report, and the Defense Threat Reduction Agency (search) was also crunching numbers.

Kerry's running mate, Sen. John Edwards, campaigning in Ohio, added, "After today, it's hard to imagine that even they'll continue believing things are going well."

On Sunday, Kerry pounced on a statement the president made about the War on Terror during an interview with FOX News' Sean Hannity that was set to air Monday night.

"Now there's a whole new interview and the president says in this interview, 'Whether or not we can be fully safe looking [into] the future is up in the air,'" Kerry said. "Well, let me tell you something, ladies and gentlemen, you make me president of the United States, we're going to win the War on Terror. It's not going to be up in the air whether or not we make America safe."

Chris Henick, a former deputy assistant to Bush, told FOX News the president was just being honest.

"All these comments by John Kerry shows [Kerry's] not being realistic," Henick said, noting that Kerry recently referred to the need to reduce the threat of terrorism to a "nuisance."

"To hear John Kerry talk about all this ... is just almost ridiculous coming in the final week," Henick said. "This final week is going to be framed by both campaigns on who has the leadership on security and safeguarding America against a terrorist threat."

But Democratic strategist Bob Beckel told FOX News Bush's head is in the clouds when it comes to the reality on the ground in Iraq and the security situation here at home.

"Somebody's got to tell George Bush and his dog they're not in Kansas anymore," Beckel said. "He's gotta get back to reality here — he's the president of the United States ... he doesn't get it."

Bush Revamping Stump Speech

Bush is getting help on the campaign trail from the man known as "America's mayor" — Rudy Giuliani (search). The former mayor of New York City stumped for the president in the battleground state of Colorado.

Monday's focus on the War on Terror includes a new television ad that closely tracks the president's remarks. With Giuliani by his side, Bush accused Kerry of not having what it takes to fight the anti-terror battle.

On Tuesday, Bush plans an address on the economy. It's an area where Kerry believes he is stronger, but Bush plans to contrast what he says is the economy-boosting impact of his tax cuts with a charge that the Massachusetts senator would raise taxes on all Americans if elected. That argument is expected at Bush appearances at three rallies in Wisconsin and one in Iowa.

By Friday, Bush will shift to the topic of leadership qualities, Bartlett said.

Also, later this week, Bush will be joined in Ohio by Giuliani and California Gov. Arnold Schwarzenegger (search). The Bush camp has retreated in some states, such as Maine and New Hampshire; aides said it's in part because they're sure of a Bush win there.

"The president still has strong campaigns in the battleground states ... we're no longer working as hard in the traditional Bush states," Bush-Cheney campaign spokeswoman Jennifer Millerwise told FOX News on Monday, adding that he will still campaign strong in Ohio and Democratic strongholds like Michigan and Iowa. "And that's because John Kerry has a record that does not match the Democrats' records in those states," Millerwise said.

Kerry campaign senior adviser Debra Deshong said it's surprising Bush has nearly pulled out of some states already.

"John Kerry's going to be campaigning in places like Ohio and Florida ... we're going to be appealing to a wide variety of undecided voters — people are still tuning into this race — people are pretty busy," Deshong said, adding that her candidate will hammer away at Bush on issues such as homeland security and various "catastrophic mistakes" made by the administration.

Millerwise also took a shot at those who would accuse Kerry of having a reputation for being a "flip-flopper" on various issues — a reputation the GOP has been pouncing on, trying to prove Kerry won't be able to stand strong if elected to the White House.

"There is not a weather vane on the White House and John Kerry can't step outside to see which way the wind is blowing that day," Millerwise said.

With only a few states left on both sides' target lists, a now familiar coincidence of scheduling has Bush and Kerry spending the night in the same state, the president in La Crosse, Wis., and Kerry about 200 miles away in Green Bay.

FOX News' Bret Baier, Ian McCaleb, Liza Porteus, Kelly Wright and The Associated Press contributed to this report.