WASHINGTON DC (CNN) -- A new poll suggests that President Bush is the most unpopular president in modern American history.

A CNN/Opinion Research Corp. survey released Thursday indicates that 71 percent of the American public disapprove of how Bush is handling his job as president.

"No president has ever had a higher disapproval rating in any CNN or Gallup Poll; in fact, this is the first time that any president's disapproval rating has cracked the 70 percent mark," said Keating Holland, CNN's polling director.

"Bush's approval rating, which stands at 28 percent in our new poll, remains better than the all-time lows set by Harry Truman and Richard Nixon [22 percent and 24 percent, respectively], but even those two presidents never got a disapproval rating in the 70s," Holland said. "The previous all-time record in CNN or Gallup polling was set by Truman, 67 percent disapproval in January 1952."

While Gallup polling goes back to the 1930s, it wasn't until the Truman years that they began surveying monthly approval ratings.

CNN Senior Political Analyst Bill Schneider adds, "He is more unpopular than Richard Nixon was just before he resigned from the presidency in August 1974."

President Nixon's disapproval rating in August 1974 stood at 66 percent

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The poll also indicates that support for the war in Iraq has never been lower. Thirty percent of those questioned favored the war, while 68 percent opposed it.

"Americans are growing more pessimistic about the war," Holland said. "In January, nearly half believed that things were going well for the U.S. in Iraq; now that figure has dropped to 39 percent."

The numbers on the Iraq war come on the five-year anniversary of Bush's "Mission Accomplished" moment on board the aircraft carrier USS Abraham Lincoln, when he proclaimed that "major combat operations in Iraq have ended."

The record-low support for the war in a CNN poll could be one reason behind the president's unpopularity, but it probably is not the only one.

"Support for the war, the assessment of the economy and approval of Mr. Bush are all about the same -- bad," Schneider said.

The CNN/Opinion Research Corp. poll was conducted by telephone from Monday through Wednesday among 1,008 adult Americans.

The poll's sampling error is plus or minus 3 percentage points. E-mail to a friend

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