George W Bush has hit back at his US presidential rival John Kerry for what he says are "wild charges" about Iraq.
A partisan crowd, including Amish supporters, greeted George W Bush
Mr Kerry is still on the attack, using reports that 350 metric tons of high explosive went missing after the US-led invasion to say Mr Bush is incompetent.
But in his first comments about the missing explosives, Mr Bush said in Pennsylvania that Mr Kerry had jumped to conclusions for political reasons.
Both candidates are campaigning non-stop, six days before the election.
With opinion polls indicating the race is still very close, correspondents say both campaigns are looking for subjects where they can win support - and Iraq remains a key topic.
Mr Bush broke his silence on the missing explosives - first reported on Monday - by repeating his charge that, if Mr Kerry had been president, Saddam Hussein would still control Iraq and have hundreds of thousands of tons of explosives to share with terrorists.
"Now the senator is making wild charges about missing explosives," he told supporters at a rally in Lancaster, Pennsylvania.
Mr Bush claimed that even Mr Kerry's top foreign policy adviser had admitted not knowing all the facts.
The Pentagon, he said, was investigating whether the explosives might have been moved before US troops had reached the site.
"A political candidate who jumps to conclusions without knowing the facts is not a person you want as your commander-in-chief," he added.
The Bush campaign also released a new TV ad, using clips from the Republican convention earlier this year when the president talks emotionally about how meeting the relatives of casualties in Iraq had reinforced his commitment to defend the US.
Mr Kerry's campaign is also running a new ad, focusing on the missing explosives and saying Mr Bush's "misjudgements" had put soldiers at risk and made the country less secure.
Mr Kerry seized on Mr Bush's comments, saying it was his opponent, not him, who was thinking only of the political impact.
KEY SWING STATES
1. Florida - 27 electoral votes
2. Pennsylvania - 21
3. Ohio - 20
4. Minnesota - 10
5. Wisconsin - 10
6. Iowa - 7
7. Nevada - 5
8. New Mexico - 5
9. New Hampshire - 4
"Because of your mistakes, you owe Americans real answers about what happened, not just political attacks," he challenged the president, during a speech in Rochester, Minnesota.
"Your administration was warned, you were put on notice but you didn't put these explosives on priority lists, you didn't think it was important.
"You didn't give the troops the instructions they need, you didn't guard the ammunition dumps and now our troops are at greater risk."
The bulk of Mr Kerry's speech, however, focused on the economy.
Aides say the Democrat's plans for foreign policy and the economy will be honed into "closing arguments" for voters to opt for change at the ballot on Tuesday.
The campaigns are expected to continue to focus entirely on the handful of states where either side could win.
After Pennsylvania, Mr Bush was travelling to Ohio and on to Michigan while Mr Kerry was due to go to Minnesota. Mr Bush won Ohio narrowly in the 2000 election but lost the other four states - some by very small margins - to Al Gore.