Ten candidates fighting to become the Democratic Party’s nominee came together on stage for the first 2020 primary debate, hosted by NBC News.

Another debate, featuring another 10 candidates, will air tomorrow. Yes, there are that many people running.

All of them want to take on Donald Trump in the general election, and it seems the President was watching today — not that he found it particularly stimulating.

Mr Trump was on his way to Japan for the G20 Summit, and presumably watched the debate on board Air Force One.

Instead of attacking the candidates or their policies, Mr Trump actually took aim at NBC, mocking it over a technical hiccup that derailed the two-hour broadcast halfway through.

Lester Holt and Savannah Guthrie moderated the first hour, then left the room, allowing Chuck Todd and Rachel Maddow to take over. But as Todd tried to ask his first question, he was interrupted by the sound of other people’s voices.

At first Todd and Maddow thought it was a microphone somewhere in the audience.

“I think we have a — I heard that too, that’s OK. I think we had a little mic issue in the back? I think we heard the audience audio,” Todd said, before recommencing his question.

He got most of it out before the disembodied voices interjected again. A man mentioned going to the bathroom. A woman said she needed to grab her binder.

It dawned on the new moderators that Holt and Guthrie's mics had not been turned off. The whole room — and everyone watching on TV — seemed to be hearing their conversation from backstage.

“There’s voices behind us!” one of the candidates, Senator Amy Klobuchar said, as the stage erupted in laughter.

“We are hearing our colleagues’ audio. If the control room could turn off the mics,” Todd said.

A few more awkward moments passed.

“If the control room could turn off the mics of our previous moderators,” Todd repeated.

“You know, we prepared for everything. We did not prepare for this,” Maddow said.

It was all taken in good humour, but NBC had to cut to an ad break to sort out the problem.

Mr Trump was not impressed, calling it “truly unprofessional” and saying the network should be “ashamed”.

The debate itself brought together a mix of prominent candidates like Elizabeth Warren, Amy Klobuchar, Cory Booker, Beto O’Rourke and New York Mayor Bill de Blasio, and those who were struggling to get attention, such as Julian Castro, Jay Inslee, Tulsi Gabbard and a couple more whose names, to be frank, don’t really matter.

The topics discussed included the economy, health care, immigration, climate change, Iran and gun control.

Ms Warren was particularly strong on the economy, where she railed against big corporations and promised to govern for ordinary people.

“I think of it this way. Who is this economy really working for? It’s doing great for a thinner and thinner slice at the top,” she said.

Mr Castro stood out during the discussion of immigration. He called for fully decriminalising the act of illegally crossing the US border with Mexico.

Other top-tier candidates will take part in their own debate tomorrow. They include former vice president Joe Biden, who is the clear frontrunner in the polls, along with former California attorney general Kamala Harris and South Bend Mayor Pete Buttigieg.

Mr Trump, meanwhile, concluded proceedings by tweeting this mocked up clip, which essentially shows him being President forever.

He really likes this particular meme; this is in fact the second time he’s posted it.

The message was pretty clear — he is confident he can beat anyone who was on stage today.