"Hey, those lips are big," Alcaraz heard a an African-American girl say from the back of the room.

Alcaraz was disturbed. "I try to bend over backwards not to make him look like a cartoon stereotype," and certainly not a racial stereotype, he said.

Editorial cartoonists are bending over backwards a lot these days, as they try to satirise the nation's first African-American President.

And when they don't, the result is the kind of outcry that erupted this week after a New York Post cartoon featured a bloody chimpanzee — intentionally or unintentionally evoking racist images of the past.

The problem is, cartoonists make their living by making fun of people — especially presidents — and exaggerating their features and foibles.

The best political cartoons are "like an X-ray machine," said Amelia Rauser, an art history professor at Franklin & Marshall College and author of Caricature Unmasked, which examines the art form's historical role in political discourse.

"You have to deform someone facially in order to make a larger point about their character," Rauser said. "But that deformity reveals their inner truth and makes them look more like themselves."

The late Herblock often saddled Richard Nixon with an enormous cartoon nose. Liberals drew George W Bush like a simpleton, or worse. There have been minor kerfuffles from the left about drawing Hillary Clinton as insufficiently feminine, and from the right about depicting Condoleezza Rice as servile to President Bush.

Drawings of President Barack Obama, however, must contend with America's history of degrading racial imagery, from ape comparisons to enormous "Sambo" lips. (Caricatures of the President's admittedly large ears have so far escaped scrutiny.)

Michael Cavna, who blogs about comics for ‘The Washington Post’, wrote that, "an unnerving number of North America's political cartoonists are bizarrely obsessed with President Obama's lips." He followed with a detailed analysis of several cartoons where Obama's lips were large, some shade of blue, or both.

On Wednesday, the ‘New York Post’ published an editorial cartoon showing a chimp shot to death by police officers. "They'll have to find someone else to write the next stimulus bill," the caption reads.

Amid widespread African-American condemnation, the Post initially defended the panel by its longtime cartoonist Sean Delonas, saying it referred to a chimp that recently attacked its owner's friend and was killed by police. The newspaper apologized "to those who were offended" after 200 protesters picketed the Post offices on Thursday.

During the Presidential campaign, The New Yorker magazine was accused of racism for an infamous cartoon of Obama dressed as a Muslim, fist-bumping his wife, Michelle, who was toting a machine gun. The magazine said it was satirising right-wing smears of the Obamas.

Scott Stantis, editorial cartoonist for The Birmingham News in Alabama, said he received several complaints this week that his Obama drawings look "simian." As a conservative in a city that's 77 per cent African-American, Stantis has learned to consider the feelings of his audience.

"Being the typical American editorial cartoonist — doughy, white, middle-aged — I'm more than willing to accept that I don't know what may or may not be offensive," he said. "But editorial cartoons are supposed to be offensive, and provocative. We're entering new waters here. What can you use or not use?"

"All my characters look simian," he said. "I don't make Obama look nearly as simian as our former Governor Fob James, who I DID draw as a monkey, on more than one occasion. And he's a white guy. ... I'm sorry, but when it comes to African-Americans, you just don't draw monkeys."

Ted Rall, President of the American Association of Editorial Cartoonists, said that Obama's race has affected how his colleagues do their jobs: "Without a doubt, people are stepping more gingerly. People are tiptoeing their way through this."

Rall, who is liberal, said it's harder to take shots at Obama because he's smart, charming and handsome, "so when you attack the personality, people suspect there's only one reason: It's gotta be his race. My conservative cartoonist friends find it very frustrating."

One of those conservative friends, Mike Lester of the Rome News Tribune in Georgia, said that when he was growing up, "if we didn't make fun of you, we didn't like you."

Perhaps race relations would improve, Lester said, if African-American people lightened up a bit: "They're not too good (at being) made fun of. We can all take a joke."

Lester said Rall told him before the election that an Obama presidency would be good for conservative cartoonists, but it's been just the opposite.

"I find myself having to temper my comments," Lester said. "I'm tired of it. (Obama) wants my money, he wants me to pay for my neighbour's foreclosed house that he can't afford. Race has nothing to do with it."

That's what Delonas said about his cartoon in the Post. So as the nation's edgy fraternity of editorial cartoonists continues to unload on Obama, lines will inevitably be crossed again.