US presidential candidate in 2020 polls, Senator Bernie Sanders, has vowed to “prevent” President Donald Trump and his National Security Adviser John Bolton from taking the country into a war with Iran, further calling the American president a “pathological liar” that’s leading the nation towards authoritarian rule.

"Right now, this minute, I am doing everything that I can -- working, by the way, with some honest conservatives in the Senate -- to prevent Donald Trump and John Bolton from taking us into a war in Iran," he declared during a speech on Saturday at his first political rally in his home state of Vermont since announcing his presidential bid in February.

The veteran senator further emphasized that he regards a US war with Iran “much more destructive, if you can believe it, than the war in Iraq,” adding that it “could lead us, literally, to perpetual warfare in that region."

Attacking the hawkish US president and his reckless political rhetoric, Sanders also said, "Sadly, we have a president who is a pathological liar and that he says whatever he wants without regard to the truth."

"You know that we have a president who has no understanding or respect for the Constitution of the United States, and the separation of powers, and is attempting to move -- every single day -- this country into an authoritarian form of government,” he stressed.

Trump ‘most dangerous’ US president in modern history

In an interview with NBC News last month Sanders had also described Trump as "the most dangerous president in the modern history of this country."

Sanders went on to underline that he was launching his campaign “with confidence, optimism and love,” adding that he refused to allow for the nation to be led by "greed, hatred and lies.”

“The underlying principles of our government will not be racism, will not be sexism, will not be xenophobia and will not be religious bigotry – and all the other mean-spirited beliefs of the Trump administration," the senator emphasized, pledging: "The principles of our government will be based on justice: economic justice, racial justice, social justice, and environmental justice.”

‘Trump has so wantonly lied and misconstrued the facts’

Another 2020 US presidential hopeful, Democratic Congressman Robert “Beto” O’Rourke of Texas also denounced Trump’s recent deployment of hundreds of troops to the Middle East, accusing him of lying and misconstruing facts in what Washington claims to be "Iran's threat."

Democratic Congressman Robert “Beto” O’Rourke of Texas (File photo)

In an interview on Saturday with CBS News ‘Face the Nation’ program that will be aired on Sunday, the lawmaker pointed to Trump’s senior aides -- including Bolton, who has a reputation for a hawkish stance against Iran – saying that the White House risked sending the US to war over "misconstrued facts."

"I have a really hard time believing this administration and believing a- a president who has so wantonly lied and misconstrued the facts at every single turn to his own gain. I'm- I'm suspicious of a national security team that has so often called for war," O'Rourke emphasized.

"You have someone in- in-- Bolton, who has publicly said that he wants regime change in Iran," he further underlined, warning that a war with the country would leave hundreds of thousands dead.

The congressman went on to stress that Trump’s decision to send troops to the region to counter a supposed threat from Iran would only provoke conflict and draw the US into war.

"President Trump is escalating tensions, is provoking yet another war in the Middle East where we find ourselves already engaged in war in so many countries- in Iraq in Syria in Yemen, not too far from there in Libya and in Afghanistan," O’Rourke warned. "[W]e don't need another war. We need to find a way to work with allies and partners and in some cases with our enemies."

Sen. Paul urges Trump not to listen to ‘neocons’

O’Rourke’s remarks echoed those of Kentucky Republican Senator Rand Paul who called on the US president to reconsider his announcement on Friday while urging Trump not to listen to "neocons" close to him in a clear reference to Bolton and Secretary of State Mike Pompeo.

US Republican Senator Rand Paul (Photo by AFP)

“This escalation doesn’t get us out of our decades long, seemingly endless wars Mr. President. Trust your instincts and follow what you ran on, not the neocons around who want to repeat past mistakes,” Paul tweeted.

‘We learned nothing from the experience in Iraq’

Yet another Democratic presidential hopeful Pete Buttigieg -- a former naval intelligence officer, Afghanistan war veteran and current Mayor of South Bend, Indiana – also blasted Trump during a Friday campaign event in New Hampshire.

Democratic presidential candidate Pete Buttigieg (photo by AFP)

Buttigieg further insisted that Trump “now seems to be setting us on a course that could lead to violent confrontation,” according to US-based Fox News.

He later told reporters that “I’m very worried because we have steps towards confrontation in Iran that almost make it seem as though we learned nothing from the experience in Iraq.”

Tehran has time and again asserted that it is not seeking war, yet stands ready to defend its interests in the region amid the US military buildup in the Middle East.