Less than two weeks before voters choose the next commander in chief, Democrat John Kerry (search) prepared to pound home his argument that President Bush's (search) conduct in Iraq isolates and weakens the United States.

"This president likes to say he's a leader," Kerry said in remarks prepared for delivery Wednesday. "Mr. President, look behind you. There's no one there. It's not leadership if no one follows."

Kerry said U.S. leaders must stop treating other countries with "contempt," driving them away from a role in Iraqi security and reconstruction. He also repeated charges that the president's conduct made the U.S. weaker, not stronger, in the war on terrorism.

"America is fighting and must win two wars. The war in Iraq, and the war on terror," he said. "Iraq was a profound diversion from that war and the battle against our greatest enemy, Usama bin Laden (search) and the Al Qaeda network. But now that we're fighting two wars, we must and we will prevail in both."

The Democrat took his security message to Iowa, one of a dwindling number of contested states that could sway the election. Kerry aide Mike McCurry said Kerry's call for new leadership in Iraq is one prong of their final arguments to sway undecided voters who see Bush on the wrong track.

"They are more and more convinced that President Bush does not deserve to be re-elected, and they are trying to get to the point where they can see and embrace John Kerry as the next president," he said.

The speech on the heels of fierce words from Bush and Vice President Dick Cheney about Kerry's fitness to make national security decisions.

Cheney on Tuesday raised the possibility of terrorists using nuclear weapons against U.S. cities and said Kerry hasn't made the case that he could handle such nightmarish scenarios.

"I don't believe it," the vice president said. "I don't think there's any evidence to support the proposition that he would, in fact, do it."

Bush, a day earlier, said the Massachusetts senator stands for "protest and defeatism" in Iraq and that Kerry would lead the nation toward "a major defeat in the war on terror."

Kerry's running mate, Sen. John Edwards of North Carolina, accused the Republicans of trying to scare the voters into re-electing the president. "While they campaign on fear, we're going to talk about the facts," he said.

Kerry plans to visit two other close states, Ohio and Pennsylvania, on Wednesday.