Bush earlier this week suggested US politics currently seem "vulnerable to conspiracy theories and outright fabrications"
Former Trump adviser Steve Bannon has said former US president George W Bush 'embarrassed himself' with a high-profile speech in which he slammed the current state of the US.
Bannon - who is the executive chairman of the far-right Breitbart News website - is a high-profile but controversial critic of traditional US politics, and yesterday called for an "open revolt" against establishment Republicans.
The controversial Trump adviser was speaking at a meeting of California Republicans, arguing: "President Bush to me embarrassed himself [...] It's clear he didn't know anything he was talking about."
Hitting out at Bush's speech as "highfalutin" and written by a speechwriter, Bannon claimed: "He has no earthly idea whether he's coming or going, just like it was when he was president of the United States."
He also suggested there has "not been a more destructive [American] presidency" than that of George Bush’s.
In a speech earlier this week, George W Bush did not name Trump directly - but the remarks were strongly critical of the current state of the nation.
He argued: "The American dream of upward mobility seems out of reach for some who feel left behind in a changing economy. Discontent deepened and sharpened partisan conflicts. Bigotry seems emboldened. Our politics seems vulnerable to conspiracy theories and outright fabrications.
"We have seen our discourse degraded by casual cruelty. At times, it can seem like the forces pulling us apart are stronger than the forces binding us together. Argument turns too easily into animosity. Disagreement escalates into dehumanisation."
He also hit out at "isolationist sentiments" and how nationalism has "distorted into nativism" - praising the "dynamism that immigration" has brought to the US.
The speech was the most strongly worded intervention yet from the 43rd US president, and came on the same day his successor Barack Obama again hit out at Trump-era politics.
Obama suggested: "Instead of our politics reflecting our values, we've got politics infecting our communities.
"Some of the politics we see now, we thought we put that to bed. It's the 21st century, not the 19th century. Come on!"