John Kerry (search) says President Bush "failed to tell the truth" about Iraq and "misled the American people," but that's as far as he seems willing to take it. He stops just short of the "l-word" — liar.

Democrat Harry Truman (search) may have been the last presidential candidate to call his opponent a liar, says Wayne Fields, an expert on political rhetoric. It just isn't something serious presidential contenders do these days.

Instead, this year's Democratic presidential nominee dips into a stack of euphemisms to suggest the president isn't telling voters the whole truth. In a more aggressive verbal assault on Bush in the last few days, Kerry has said:

—"The first and most fundamental mistake was the president's failure to tell the truth to the American people."

—"The president also failed to level with the American people about what it would take to prevail in Iraq."

—"The president cannot deny that they have not achieved what they said they've achieved. They've misled the American people."

—"I think he's living in a make-believe world," Kerry told The Associated Press hours after declaring that Bush lived in a "fantasy land."

Kerry's surrogates haven't felt quite as restrained.

"Let us be crystal clear. Let there be no illusions as it relates to Iraq," Democratic National Committee Chairman Terry McAuliffe (search) said at a fund-raiser in New York. "George Bush lied to the American public. He lied to the world."

Even the candidate's running mate, John Edwards (search), accused Bush of responding to Kerry's recent speech on the situation in Iraq "with more lies about John Kerry."

But it's risky to say or insinuate that Bush is lying, says Allen Louden, an expert in political rhetoric at Wake Forest University.

"If you're calling someone a liar essentially, you better darn well be right," Louden said. "It's a really risky thing to decide that your president's lying, so you just cognitively try to resist that."

Aides say Kerry isn't trying to insinuate that Bush is a liar without flat out calling him one.

"He's obviously not calling the president a liar," said spokesman Mike McCurry.

McCurry said Kerry is trying to show that Bush's portrayal of the security situation in Iraq and the U.S. economy, for example, doesn't match Kerry's understanding of the facts.

"Either he is so rigidly certain that his vision is correct that he can set aside contradictory information and not absorb it, which is a damning comment," McCurry said, "or that he in fact gets this information and chooses not to share it with the American people, in which case he is deliberately misleading them."

In response, Bush campaign spokesman Steve Schmidt called Kerry's rhetoric a "preposterous" attempt to get ahead in the polls, some of which show a close race or with Bush slightly ahead.

"He has resorted to a fundamentally dishonest campaign to try to tear down the president," Schmidt said.

Anne Demo, a communications professor at Vanderbilt University, said there are few instances where a politician can be provably caught lying. She sees Kerry's rhetoric as encouraging voters to conclude for themselves that Bush is lying.

"They translate mislead into lie," she said.

By not speaking the word "liar," Kerry skirts a debate over his choice of word. The focus stays on his portrayal of Bush as a leader painting rosy pictures over what Kerry says is a failed record, and Kerry avoids the awkward situation of being accused of lying about whether the president is lying.

"The idea of lying is that you know and you told something different than what you knew the truth to be," said Fields, a professor at Washington University in St. Louis. "He's got to be careful that he doesn't accuse them of a lie when it's only an incomplete telling of the truth. They will nail him."