The Notting Hill actor issued the verdict when asked in an interview earlier this week about the Conservative Party’s recent landslide election majority.
Referring to Mr Grant’s canvassing for the Liberal Democrats’ Luciana Berger and Labour during the December campaign, the interviewer asked him: “I’m just wondering, how are you feeling now everything’s kind of settled?”
“No, it’s a catastrophe,” Mr Grant said.
The reporter asked: “So no… bright light on the horizon?”
“No, no, the country’s finished,” Mr Grant said, sat alongside his The Gentleman co-star Charlie Hunnam.
It prompted his Mr Morgan to lash out on Sunday morning, reigniting a bitter feud between the pair.
Hugh Grant is so disgusting.
How dare he say Britain is 'finished'?
The only thing that's 'finished' is this stuck-up arrogant twerp's credibility as any kind of political expert. https://t.co/2ib7gWk7Tm— Piers Morgan (@piersmorgan)January 26, 2020
“Hugh Grant is so disgusting. How dare he say Britain is ‘finished’?,” the GMB host tweeted.
“The only thing that’s ‘finished’ is this stuck-up arrogant twerp’s credibility as any kind of political expert.”
The tweet, liked more than 11,000 times, saw a flood of comments railing against the actor, but others mocked Mr Morgan for having another outburst.
The pair clashed last December over Boris Johnson’s victory, with the breakfast presenter telling Mr Grant to “stick to acting” instead of wading into politics.
“Hugh campaigned for four different Labour and Lib Dem candidates… and all four lost,” he said, branding him a “fool saint”.
“So well done Hugh, really magical performance. Maybe next time just stick to the acting, stick to the Love Actually reruns. They air this time of year. We can all watch it quite like you. Just don’t talk about something you know nothing about."
Mr Morgan also taunted the actor summer after he called the prime minister an "over-promoted rubber bath toy", tweeting along with a mug shot from his 1995 arrest: "Halo Hugh... Britain's moral standard-bearer".