President Bush has been effective before. After his March 17, 2003 speech before the war in Iraq began, approval of his handling of Iraq rose 10 points -- from 53% before the speech to 63% afterwards. And speech watchers were more than twice as likely to say they were relieved as to say they were worried.
Other Presidents have also given speeches that affected public opinion positively. Bill Clinton's approval rating rose 16 points after his State of the Union address in January 1998, shortly after revelations of his relationship with Monica Lewinsky surfaced. In 1983, Ronald Reagan's speech after the invasion of Grenada resulted in public support for the invasion jumping from 46% before to 55% after.
But there was little change after last night's speech. Six in ten Americans opposed sending more the 20,000 additional troops to Iraq – and it mattered little whether they watched the speech or didn't. Worse for the President, perhaps, is that personal assessments of him didn't change, Before the speech 68% of Americans said they were uneasy about the President's ability to make the right decision about Iraq,. After the speech that number was still 68%.
Of course, opinions may change over the next few days as more information is available and more arguments are made. But right now, these poll results suggest that opinion about the war in Iraq may have hardened – just as it did in 1967 and 1968 about the war in Vietnam, and just as it did in 1973 and 1974 about Watergate. No event – and perhaps no single speech – could unharden those opinions.