<p>April 6, 2004 -- WASHINGTON - Sen. Ted Kennedy yesterday charged that President Bush's credibility was no better than Richard Nixon's - drawing an immediate rebuke from Republicans. A Kennedy spokesman said Sen. John Kerry's campaign was given advance warning of the scathing speech from one of its top supporters, but denied that Kerry consulted with Kennedy on it. In his remarks to the Brookings Institution, a think tank in D.C., Kennedy also said, "Iraq is George Bush's Vietnam."</p>