In a new book, Chafee, who is backing Clinton rival Sen. Barack Obama, skewers Clinton and other Democratic White House hopefuls who said they were duped by Bush into voting for the war.
"Being wrong about sending Americans to kill and be killed, maim and be maimed, is not like making a punctuation mistake in a highway bill," Chafee writes. "They argue that the president duped them into war, but getting duped does not exactly recommend their leadership. Helping a rogue president start an unnecessary war should be a career-ending lapse of judgment, in my view."
Chafee says top Democrats put their political ambitions first in the fall of 2002.
"They were afraid that Republicans would label them soft in the post-September 11 world, and when they acted on that political self-interest, they helped the president send thousands of Americans and uncounted innocent Iraqis to their doom," he writes.
Last year, Chafee changed his party affiliation and became an independent. He recently endorsed Obama, who spoke out against the war in 2002 as an Illinois state lawmaker.
Chafee's hopes for a second full term in 2006 were dashed by Democrat Sheldon Whitehouse. Clinton was among leading Democrats, including Senate Majority Leader Harry Reid of Nevada, who campaigned in Rhode Island for Whitehouse.
Chafee's book is titled "Against The Tide: How a Compliant Congress Empowered a Reckless President." He succeeded his father, the late Sen. John Chafee, in the Senate in 1999 after the elder Chafee's death.
