NEW YORK — It is a date that will live in…well, not infamy, but a date that will dwell in discomfit for the Bush administration. It was on May 2, 2003, when the president appeared on the deck of the aircraft carrier USS Lincoln to announce the end of major military combat operations in Iraq, as a banner behind him proclaimed “Mission Accomplished.”

Much of the debate has focused on whether that mission really has been accomplished (a recent CNN poll found that only 9 percent believe that it has), but there’s a striking political lesson that’s been overlooked. It’s not that the president hasn’t been taking his case to the public — indeed, he’s done that repeatedly. What’s happened is that the public has stopped buying the message.

All through the second term, Bush has been using the “bully pulpit” of the presidency to argue his case on the war in Iraq — and the broader “war on terror.” All the power of the White House has been brought to bear — the speeches have been carried live on cable news and have received major coverage. And what has happened?

Approval ratings — on Iraq, on terror and on job approval in general — have steadily fallen.

On April 12, 2005, a day when the president gave a speech to military families on terror, Bush’s job approval rating was at 50 percent. Two months later, he made a visit to the National Counterterrorism Center and then gave a nationally televised speech to the nation from Fort Bragg. By month’s end, his job approval was at 45 percent.

Last November, the president visited the U.S. Naval Academy at Annapolis and Elmendorf Air Force Base to talk about terror and Iraq. By year’s end, his job approval was at 41 percent.

So far in 2006, Mr. Bush has given this year six speeches on terror and Iraq, not counting the State of the Union. What has happened? He began the year at 43 percent job approval — in CNN’s latest polling, he’s at 32%. And his handling of Iraq — and terror in general — are now sharply negative.

What has happened? Put simply, it’s that the power of a president, with all the attention that office commands, is no match for a steady stream of unsettling news. Every piece of good news — a referendum, an election — seems overshadowed by violence that takes both Iraqi and American lives.

Even more important, much of the negative news has come not from political foes, but from retired generals and, most recently, from former Secretary of State Colin Powell, saying, yes, he wanted more troops to secure Iraq.

Every White House loves to argue that its best weapon is the president, connecting directly with the people, and this White House has been relentless in the belief that when the president goes to the country, surrounded by respectful, if not admiring citizens, with the slogan of the day emblazoned in the background, it will be politically effective. But at least for the moment, such tactics appear to be as effective as the repeated effort of a computer user to hit the “enter” or “escape” button when the machine freezes up.