The town hall debate between Hillary Clinton and Donald Trump turned ugly very quick, with each candidate hurling attacks based mostly on previous issues that had been a part of a campaign that seems like it has been going on for forever.

But Trump launched something very new on Sunday, something that many people feel crossed a line.

SEE ALSO: Trump lurks like a hungry ghost behind Clinton during entire debate

During one particularly contentious exchange, Trump pledged that if he won the presidency, he would appoint a special prosecutor to investigate Clinton's use of a private email system during her time as the secretary of state.

"You'd be in jail," Trump said to Clinton.

The moment came and went relatively quickly, with numerous other moments gaining plenty of attention.

The pledge, however, stuck with many as a particularly terrifying statement.

Former attorney general Eric Holder weighed in, noting that Richard Nixon attempted a similar maneuver — an action that resulted in the resignation of his attorney general.

So @realDonaldTrump will ORDER his AG to take certain actions-When Nixon tried that his AG courageously resigned. Trump is dangerous/unfit — Eric Holder (@EricHolder) October 10, 2016

Trump's campaign felt the moment was strong enough to tweet out.

Plenty of other politics watchers also noticed the moment.

Trump says to Clinton, if he was in charge, “you’d be in jail.”



This is an overt subversion of democracy. It is very hard to overstate this — Max Fisher (@Max_Fisher) October 10, 2016

Ttrying to get my head around a candidate declaring if he wins he'll get Justice Dept to appoint a special prosecutor to lock up opponent — Andrea Mitchell (@mitchellreports) October 10, 2016

Trump says he wants to put his political competitors in jail. Think about that. That's what violent dictators do. — Adam Ellis (@moby_dickhead) October 10, 2016

If you don't think Trump wants to mirror Putin as President, then you didn't hear him threaten to jail his political rival if elected. — Chris Murphy (@ChrisMurphyCT) October 10, 2016

HE

PLEDGED

TO

PUT

HIS

POLITICAL

OPPONENTS

IN

JAIL



Everything else is a detail — Dana Houle (@DanaHoule) October 10, 2016

When Trump said he would jail Hillary, I heard the keys of the warden rattle. How many others - political opponents - would be in jail? — Jeffrey A Tucker (@jeffreyatucker) October 10, 2016

A candidate promising to personally instruct that his opponent be prosecuted (and jailed?) if he wins does not believe in the rule of law. https://t.co/scvFZO2IhQ — Jonathan Zittrain (@zittrain) October 10, 2016

I would like the moderators to revisit the threat, made by Trump, to prosecute and jail his political rival if he wins the presidency. — Jeffrey Goldberg (@JeffreyGoldberg) October 10, 2016

I just thought about how wild it is the Donald Trump literally said that he would throw his political opponent in jail if he was elected. — Clint Smith (@ClintSmithIII) October 10, 2016

He said "you'd be in jail." Sorry , Trump insults our foundling fathers with threats like that. https://t.co/3AM9kU5oJ8 — Michael McFaul (@McFaul) October 10, 2016

For real, for a candidate to threaten another candidate with prosecution and jail is strong-arm, dictator, despot behavior. Crazy and wrong. — Brian Koppelman (@briankoppelman) October 10, 2016

BONUS VIDEO: Watch Trump lurking behind Clinton during the debate.