When asked how can he, if elected, keep the pledge not to raise taxes as the price of everything is going up, Kerry said he will restore fiscal discipline and roll back Bush's unaffordable tax cut.

"We're going to restore the fiscal discipline we had in the 1990s. Every plan that I have laid out...I've shown exactly how I'm going to pay for those," Kerry said in the debate in Tempe, Arizona.

The 90-minute debate, which started at 9 p.m. EST (0100 GMT), is the only one devoted to domestic issues such as jobs, health care and Social Security.

"We don't do it exclusively, but we start by rolling back George Bush's unaffordable tax cut for the wealthiest people, people earning more than 200,000 dollars a year," Kerry said.

Bush cited Kerry's voting record in the Senate to warn that Kerry would raise taxes.

"He's been a senator for 20 years. He voted to increase taxes 98 times. When they tried to reduce taxes, he voted against that 127 times," he said.

"He talks about being a fiscal conservative or fiscally sound, but he voted over -- he voted 277 times to waive the budget caps, which would have cost the taxpayers 4.2 trillion dollars," Bush added.

Bush said Kerry proposed 2.2 trillion dollars of new spending, and yet the so-called tax on the rich Kerry planed to roll back would only raises 600 billion or 800 billion dollars.

"There is a tax gap. And guess who usually ends up filling thetax gap. The middle class," Bush said.