US Senator Bernie Sanders has issued a powerful call to oppose American President Donald Trump.

In an opinion piece published by The Guardian, Sanders wrote that "Trumpism can and must be defeated", highlighting the importance of defeating the upcoming 'reconciliation bill'.

Set to be brought forward in the coming weeks,  Sanders said the bill "encapsulates the value system of greed and their obedience to oligarchy."

"At a time of unprecedented income and wealth inequality, this legislation will provide trillions of dollars in tax breaks to the richest people in our country," he added. "It will make the rich even richer. At a time when the working class of this country is struggling to put food on the table and pay for housing, this legislation will make savage cuts to Medicaid, housing, nutrition, education and other basic needs. It will make the poor even poorer.

"We cannot allow this to happen. This legislation is enormously unpopular. It is exactly what the American people do not want. It must not be passed by Congress."

Elsewhere in the piece, the Vermont Senator lambasted the American President's ties to billionaires such as Elon Musk and right-wing publications, as well as Trump's tactic of "flooding the zone" to consume overwhelming media attention. Sanders also underlined the importance of establishing free healthcare and education, affordable housing and abolishing "all forms of bigotry".

"Not only must we continue to fight for a nation based on the principles of economic, social, racial and environmental justice, we must also lead the effort against Trump‘s reactionary legislative agenda," he said.

Sanders' comments arrive on the same day that Donald Trump seemingly blamed Ukraine for their ongoing war with Russia, after Ukrainian and European officials were left out of US-Russia talks in Riyadh.

“But today I heard: ‘Oh, well, we weren’t invited'", Trump said. "Well, you’ve been there for three years. You should have ended it three years. You should have never started it. You could have made a deal.”

These false claims were made despite Russia's invasion being considered an unprovoked and widely condemned act by the international community.