Marion, Iowa: Democrat Barack Obama sharply criticised Hillary Clinton on Sunday for her past support of the North American Free Trade Agreement, saying the former first lady had changed her mind about the trade agreement only after becoming a presidential candidate.

"I think it's important to note that Senator Clinton was a cheerleader for NAFTA for more than a decade," Senator Obama said at a news conference where he accepted the endorsement of a regional chapter of the United Auto Workers.

Smart campaign

"I realise that changing your position to suit the politics of the moment might be smart campaign tactics but isn't the kind of strong, principled leadership America needs right now," Obama said. He commented at the start of a two-day swing through Iowa, where the voting begins on January 3.

Polls show Obama, Clinton and former North Carolina senator John Edwards in a tight race in Iowa even as Clinton holds a wide lead in most national surveys. All three candidates are campaigning in the state in the run-up to the Thanksgiving holiday.

Obama, whose largest base of support lies with affluent and well-educated voters, has sought to burnish his credentials among middle- and working class Democrats.

Polls show Clinton running strong among those voters, while Edwards has run a tough-talking populist campaign aimed at wooing that group as well.

NAFTA was passed in 1993 with the strong support of President Bill Clinton, and eliminated most tariffs on goods traded between the United States, Canada and Mexico.

Since then, many Democrats and representatives of organised labour have roundly condemned NAFTA, arguing that it has favoured the rich while moving thousands of middle-class jobs out of the United States.

Edwards has called the agreement a "disaster". When pressed at a televised debate on Thursday on whether she still supported NAFTA, Clinton said the agreement had been a mistake "to the extent that it did not deliver on what we had hoped it would." Obama took note of those words Sunday.

"I was pleased to hear her say that because as more than 10,000 jobless Iowans know, that's what NAFTA has been," he said.

Obama also denounced as "slime politics" a flap created by a column published Saturday by conservative journalist Robert Novak.

Rindge, New Hampshire (AP) Making people angry is a good thing, presidential hopeful John McCain said in a speech aimed at playing up the Republican senator's outsider reputation.

"I didn't seek public office to go along, to get along," McCain said, trying to remind voters of the "maverick" label that helped him defeat then-Texas Governor George W. Bush in New Hampshire presidential nominating primary in 2000.

"I went to Washington to get something done for the people who sent me there. And since then, I know I've made some people angry." McCain said Democratic candidate Hillary Clinton has done everything she can to land on the popular side of most issues.

"On the one hand, Senator Clinton says we can't abandon Iraq to Al Qaida and the influence of Iran. On the other, she wants a firm deadline for withdrawal that would do just that," McCain said.

"Senator Clinton rejected unconditional talks with Iran, but now says she would negotiate with no preconditions."