Challenging President Bush on his home turf, John Kerry (search ) decried a "four-year trail of broken promises" that he said have left economic ruin and given free rein to corporate polluters.

"George Bush is a walking contradiction and a walking barrel of broken promises," the presumptive Democratic presidential candidate said Saturday, speaking to several hundred supporters at a community college.

Video: Carl Cameron interviews John Kerry.

Kerry was broadening his populist economic themes to challenge Bush on the environment and his handling of conflicts abroad as, not far away, the president sought to cast himself as a world leader in a summit with Mexico's president, Vicente Fox (search ).

The two rivals traced early outlines of a coming economic fight that is likely to be central to the campaign.

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Speaking with reporters at his Crawford, Texas, ranch, 206 miles from Kerry's event in Houston (search ), Bush defended his handling of the economy, saying "our economy is getting stronger" and suggesting that Kerry's proposals would raise taxes.

"Raising taxes will make it harder for people to find work," Bush said. Kerry has called for repealing the portions of Bush's tax cut that went to wealthy taxpayers, a move that Bush characterizes as a tax increase.

Kerry fired back quickly, using a San Antonio rally to contend Bush has "already departed from the truth."

"Once again President Bush has told one of those tall Texas tales," he said. "I think George Bush ought to leave the ranch and come out and talk to people who have lost their jobs."

Kerry casts his proposal in terms of using proceeds of a canceled tax break for the wealthy to pay for crucial education and health programs that have suffered under Bush's watch.

"The people I've met here in Texas and all across America aren't asking for much," Kerry said at a town-hall style meeting. "All they want is a government that honors their values and helps them build a better life."

Kerry sought to personalize his populist economic theme, listening to stories from local residents who said they've suffered because of deep cuts in programs Kerry argued have been battered under Bush's watch.

The Massachusetts senator sought to underscore his message by pointing out economic pressures that have hit Texas with a loss of 84,000 jobs.

"Houston, we've got a problem," he said.

While Kerry sought to make the economy the main focus of his four-day Southern swing, he also made it clear he'll challenge Bush on the president's conduct of the war in Iraq, using his background as a decorated veteran to claim credibility.

At a stop in San Antonio, Kerry was to meet with a woman who lost her son in Iraq.

"The first definition of patriotism is keeping faith with those who have worn the uniform of the country," said Kerry, who argued in the Democrats' weekly radio address that Bush has not given the troops sufficient logistical support.

That drew an immediate response from Bush campaign spokesman Scott Stanzel, who said Kerry's charge was "the latest example of his astonishing ability to say one thing and do another." He accused Kerry of voting against money to pay for the troops.

In Houston, Kerry derided Bush's new television ads that promote his re-election as the man who led the country safely through perilous times.

"About the only promise we can expect George W. Bush to keep this time around is his pledge of steady leadership," said Kerry. "He has no problem campaigning on the same failed economic policies that have steadily led America into economic decline."

Just days after forcing the last of his rivals from the race for the Democratic nomination, Kerry was seeking to show the flag in the South, probably his toughest region in which to build support. He was spending Saturday in Texas before flying to Mississippi.

While few argue seriously that the president's home state or reliably Republican Mississippi are up for grabs in the November election, campaign aides said Kerry was making the point that he'll compete everywhere. He was heading later to Florida, a crucial swing state.

Kerry argues that his focus on jobs and the economy will sell in all regions, but the issue of Iraq and the war on terror injected itself into the fray on Saturday.