TV ratings for the first prime-time Republican debate of the 2016 campaign won't come out until later Friday, but we already know how the event -- co-hosted by Fox News Channel and Facebook -- played out on social media. According to both Twitter and Facebook, the most talked-about moment on each platform was a heated exchange between New Jersey Gov. Chris Christie and Sen. Rand Paul of Kentucky, who traded barbs over the National Security Agency’s controversial surveillance program.

The argument between Christie and Paul stemmed from the candidates’ disagreement over the effectiveness and legality, or lack thereof, of the NSA’s phone surveillance program. In his defense of the program, Christie invoked a need to keep Americans safe from terrorism post-9/11, while Paul asserted that the collection of phone records without warrants violates the Fourth Amendment of the U.S. Constitution.

“I don’t trust Obama with our records,” the Kentucky senator said. “I know you gave him a big hug, and if you want to give him a big hug again, go right ahead.” [Paul was referring to a Christie embrace of President Barack Obama when the president arrived in New Jersey to survey the state's damage from Superstorm Sandy in 2012.]

The outspoken New Jersey governor replied, “The hugs I remember are the hugs that I gave to the families who lost their people on September 11th. Those hugs had nothing to do with politics.”

Businessman Donald Trump, whose outrageouness has been dominating the election coverage, also had a big night on social media. According to the official Twitter Government account, he was the most mentioned candidate during the GOP debate. Similarly, the former overlord of NBC's "The Apprentice" was also the most discussed candidate on Facebook, reports the Mark Zuckerberg-led social network. 

Trump's pervasiveness on social media isn't entirely surprising. Between May 29 and July 28, 26.2 million unique people on Facebook made 135.6 million interactions related to him -- that’s the most of any GOP candidate -- reported Facebook. In this context, "interactions" means likes, posts, comments and shares. 

According to Facebook, 7.5 million users in the U.S. made 20 million interactions related to Thursday night’s two-hour debate.

Facebook doesn’t have any data from debates from the previous election cycle to which last night’s numbers can be compared; however, this debate was a pretty huge hit on the social network when compared with other recent political events. Obama’s most recent State of the Union address, for example, generated 14 million interactions from 5.6 million people in the U.S.

Here's the rest of the Facebook data: 

Top candidate discussed during the debate on Facebook:

  1. Donald Trump
  2. Ben Carson
  3. Rand Paul
  4. Mike Huckabee
  5. Chris Christie

Top issues discussed during the debate on Facebook:

  1. Immigration
  2. Racial issues
  3. The economy
  4. Education
  5. Abortion