Nearly two-thirds of respondents in an Associated Press poll said they believe it's prudent to hold off on more tax cuts.    ...   When asked about new tax cuts, a centerpiece of President Bush's domestic agenda, 64 percent said it was better to hold off to make sure the federal budget does not go into a deeper into the red. About three in 10, 28 percent, said they favored additional tax cuts to stimulate the economy, according to the poll conducted for the AP by ICR/International Communications Research of Media, Pa.