Sen. Bernie Sanders listens to Hillary Clinton's opening statement at the Democratic presidential debate at St. Anselm College in Manchester, New Hampshire, Saturday night. Reuters/Brian Snyder

Vermont Sen. Bernie Sanders returned repeatedly Saturday night to a certain Middle Eastern monarch: King Abdullah II of Jordan. He cited the Hashemite kingdom as a moderate Muslim country and praised the king later in calling for a regional, Muslim coalition to defeat the Islamic State militant group.

"I think one of the heroes we should recognize in the Middle East is King Abdullah II of Jordan," he said.

His words caught attention on Twitter, for two main reasons: One was a gaffe by New Jersey Gov. Chris Christie during Tuesday's Republican presidential debate when he said, "When I stand across from King Hussein of Jordan, and I say to him, 'You have a friend again, sir, who will stand with you to fight this fight,' he'll change his mind."

King Hussein, the father of King Abdullah II, died in 1999.

Sanders, at least, came closer to getting the king of Jordan correct. As the Associated Press took note, Sanders did at one point call him "Abdul," not Abdullah.

For others, it's the stark difference difference between Sanders' self-declaration as a socialist and Abdullah's position as a hereditary monarch that merits attention. From the political unrest that swept many countries in North African and the Middle East, the so-called Arab Spring that began five years ago in Tunisia, Abdullah emerged largely unscathed, unlike rulers in Syria, Egypt, Libya and Tunisia.

Sanders has praised King Abdullah prior to Saturday's debate. As the leftist Jacobin magazine remarked in an article in November, "It is never a good look for a socialist to praise a monarch," highlighting the fact that Jordan, while considered a valuable ally as one of the most stable countries in the Middle East, has repressive laws of its own.