WASHINGTON: Just as Barack Obama was warning that America is in the grip of a politics of fear that undermines norms and political accountability, President Donald Trump was unleashing his latest assault on traditions of governance that underpin the nation's democracy, reports CNN.

"These are extraordinary times. Dangerous times," Obama warned in an extraordinary indictment of the behavior of a successor to whom he handed power in January 2017 and who has torn at the conventions that restrain presidents ever since.

It was a revealing moment in an enthralling clash of philosophy, temperament and style that unfolded Friday between a current and former president who epitomize opposing currents in an epochal political moment and are now in direct conflict ahead of the midterm elections.

The campaign trail face-off between Obama and Trump also capped a consequential week that saw the awakening of the Washington establishment after John McCain's funeral turned into an indictment of Trumpism and in which Trump battled an enemy within his own administration.

Obama, ditching his self-imposed political exile, warned of a moment of unique national peril, in which demagogic forces -- aka Trump -- are undermining the structures of democratic government to build their own omnipotence.

"They start undermining norms that ensure accountability and try to change the rules to entrench their own power," Obama said in a major speech in Illinois.

"It shouldn't be Democratic or Republican to say that we don't pressure the attorney general or FBI to use the criminal justice system as a cudgel to punish our political opponents -- or to protect members of our own party from prosecution just because an election's coming up," he said. At almost the same moment, aboard Air Force One, the current President told reporters he wanted Attorney General Jeff Sessions to hunt a senior official within his administration who sent the White House reeling with a devastating anonymous New York Times op-ed that branded him unfit for power.

"Here's criticism where you can't fight back. 'Cause you have somebody doing it anonymously," Trump said, after effectively ordered the criminal investigative functions of the state to purge an opponent who has not committed a crime but has merely exercised a First Amendment right.

It was far from the first time Trump has appeared to shun conventions designed to shield the instruments of justice from political interference.