Sen. John McCain compared Iran President Mahmoud Ahmadinejad to a monkey on Twitter. The Monday morning tweet was even enough for a new Republican congressman to call out the former GOP presidential candidate.

“So Ahmadinejad wants to be first Iranian in space - wasn't he just there last week?” McCain wrote to accompany a link to a story about Iran’s new space prospects.

The tweet instantly drew ire and attention. It was favorited more than 500 times and retweeted nearly 2,000 times. While some thought McCain’s joke was pitch perfect, most people were not on board.

“Look at this racist arsehole! @SenJohnMcCain that's right a brown man is a monkey. How is this acceptable?” wrote Hocine Dimerdji.

@SenJohnMcCain Not nice coming from such a senior statesman. Not nice at all!! The elected President of another country is a monkey?” added Kamran Shafi.

Less than an hour after McCain tweeted the comment, he asked people to “lighten up,” reminding people it was only a joke. That followup was enough to get a response out of Michigan Congressman Justin Amash, a Republican and second generation Arab-American. Amash, 32, was elected in 2010.

“Maybe you should wisen up & not make racist jokes,” he shot back at McCain.

Monday’s incident isn’t the first time McCain raised eyebrows on Twitter with his commentary on foreign heads of state. In 2011, McCain criticized Russia's president, Vladimir Putin, on Twitter, saying that the “Arab Spring is coming to a neighborhood near you.” The tweet resulted in Putin calling the Republican “nuts.”

Photo via Gage Skidmore/Flickr