US President Donald Trump on Thursday urged "patriotic" teaching in schools and railed against anti-racism training that he said is destroying national unity.

"The only path to national unity is through our shared identity as Americans. That is why it is so urgent that we finally restore patriotic education to our schools," he said at an event titled the "White House conference on American history."

Trump called for "a pro-American curriculum that celebrates the truth."

"Our youth will be taught to love America with all of their heart, all of their soul," he said.

Behind in the polls six weeks before the presidential election, Trump is going all out to stir up his right-wing base against what he argues is a far-left plot to change the American way of life.

He has taken particular aim at so-called critical race theory, racial sensitivity training and attempts to reexamine US history by centering the deep roots of racism against African Americans.

Trump, whose speech marked Constitution Day, was speaking after a summer of sometimes violent anti-police protests, triggered by high-profile shootings and killings by officers of black suspects during arrests.

The unrest, which activists say reflected pent-up anger at the country's failure to reckon with racism, also saw crowds tearing down historic statues -- some celebrating figures from the slave-owning South in the Civil War and some representing the country's early founders.

"We are here today to declare that we will never submit to tyranny. We will reclaim our history, and our country, for citizens of every race, color, religion and creed," Trump said.

"The left-wing rioting and mayhem are the direct result of decades of left-wing indoctrination in our schools."

He called revisionist history projects and racial sensitivity training "toxic propaganda -- an ideological poison that, if not removed, will dissolve the civic bonds that tie us together, will destroy our country."

Trump noted he had recently banned such training "in the strongest manner possible" from federal offices.