"If there is an actual major terrorist attack, civil liberties will be effectively dead in this country, no matter who is elected," Giraldi said, predicting expanded surveillance and arrest powers for federal authorities.
Whoever wins the November 8 election, Giraldi said, the next president will likely preserve the national-security regime George W. Bush established and his successor, Barack Obama, has maintained.
"Obama is already pretty draconian. I would expect either Trump or Clinton to follow suit with Clinton possibly the harsher of the two," Giraldi explained. "I don't think the harsh rhetoric during the US election campaign will lead to an increased crackdown on dissent after January."
"The impetus is already there because of our own foreign policy, with its emphasis on destabilizing much of the world, even at the risk of a war, and suppressing any dissent to that objective," he said. "It has already begun."
Pierce pointed out that Obama’s unsubstantiated allegations that Russia has been waging cyber warfare against US institutions had already been used by Vice President Joe Biden to justify potential US cyberattacks against Russia.
"When the Obama administration recently announced that it is planning an ‘unprecedented cyber covert action against Russia,’ the first victim was not Russia but [WikiLeaks founder] Julian Assange, whose internet was cut off just a day after Biden’s proclamation," Pierce recalled.
John Kiriakou, a former CIA counterterrorism officer who became a whistleblower, told Sputnik the current climate of fear has been seen before in US history.
"As ugly as things are in this election, they are not unprecedented," he said. "Indeed, several presidential elections in the 19th century and early 20th century were far worse. We Americans just don't know our history."
"I'm not detecting any fear of a terrorist attack in the run-up to the election. I think the CIA, FBI, NSA, and other alphabet agencies have — or at least believe that they have — a handle on things," he said.
However global peace campaigner Helen Caldicott, founder of the Nobel Peace Prize-winning Physicians for Social Responsibility, expressed concern that a climate of repressing speech will intensify regardless of whether Clinton or Trump wins the election in 12 days.
"The Trump campaign is run solely on fear, and Hillary Clinton has never seen a war she didn’t like," Caldicott said. "She also really runs on fear, but from a different direction."
Caldicott pointed out that, historically, terrorist attacks have frequently been used in the United States as justification to further tighten ruling elites’ hold on power and stifle criticism.
"Terrorist attacks are always useful for the establishment to crack down further on civil liberties, "she explained.
"The next administration will continue to invoke the threat of ‘other’ anti-West terrorism, real or imagined, as it has proven useful to the national security state to justify attacks on civil liberties, more surveillance and crackdowns on whistleblowers," he said.
Grosscup predicted further limits on open debate and free speech in the country, saying these are likely to be justified by, and go hand-in-hand with, heightened fear and animus toward nations such as Russia and China.
"Most importantly, it [will be] used to mobilize support for or counter objections to perpetual war against ‘immediate enemies,’" the professor asserted.
If Clinton is elected president, her support among neoconservatives is likely be used by her administration to claim a "bipartisan" consensus for further eroding speech, according to Grosscup.
Washington long ago began developing the massive institutions of national surveillance and control it would need to enforce such policies, he observed.
"The national security institutions are already in place to project US power at home and abroad in this two-front battle that is certain to suck up more and more resources," he concluded. "As in the Cold War, transparency and dissent will go by the wayside. It is a recipe for disaster."
Previous eras of US history in which civil liberties were repressed or dissidents faced broad threats include the so-called Red Scare of 1919 and the hunt, during the 1950s, for communist traitors by Republican senator Joseph McCarthy and the Un-American Activities Committee in Congress.