Politicians lined up to celebrate the downfall of Boris Johnson on Thursday, casting the British leader as a "stupid clown" who had finally got his just reward for arming Ukraine against Russia.

Johnson, the face of the 2016 Brexit campaign who won a resounding electoral victory in 2019 before leading the United Kingdom out of the European Union, announced he was quitting on Thursday after he was abandoned by ministers and most of his Conservative lawmakers over a series of scandals.

The Kremlin said it didn't like Johnson either.

"He doesn't like us, we don't like him either," Kremlin spokesman Dmitry Peskov said shortly before Johnson stood in Downing Street to announce his resignation.

In his speech announcing he was stepping down as Conservative Party leader but planned to stay on as prime minister until a replacement was picked, Johnson addressed the people of Ukraine, pledging that Britain would "continue to back your fight for freedom for as long as it takes".

Russians were brutal in their assessment of Johnson, who just recently was telling colleagues that he wanted to stay in power longer than Margaret Thatcher - a steady foe of the former Soviet Union who served as British prime minister from 1979 to 1990.

Russian tycoon Oleg Deripaska said on Telegram that it was an "inglorious end" for a "stupid clown" whose conscience would be blighted by "tens of thousands of lives in this senseless conflict in Ukraine".

"The clown is going," said Vyacheslav Volodin, the speaker of Russia's lower house of parliament. "He is one of the main ideologues of the war against Russia until the last Ukrainian. European leaders should think about where such a policy leads."

Even before President Vladimir Putin ordered the Feb. 24 invasion, Johnson had repeatedly criticised Putin - casting him as a ruthless and possibly irrational Kremlin chief who was imperiling the world with his crazy ambitions.

After the invasion, Johnson made Britain one of the biggest Western supporters of Ukraine, sending weapons, slapping some of the most severe sanctions in modern history on Russia and urging Ukraine to defeat Russia's vast armed forces. He has twice traveled to Kyiv to meet Ukrainian President Volodymyr Zelenskiy.

Maria Zakharova, the top spokeswoman in Russia's foreign ministry, said Johnson's fall was a symptom of the decline of the West, which she said was riven by political, ideological and economic crisis.

"The moral of the story is: do not seek to destroy Russia," Zakharova said. "Russia cannot be destroyed. You can break your teeth on it - and then choke on them."

Johnson's support of Ukraine has been so staunch that he has been affectionately known as "Borys Johnsoniuk" by some in Kyiv. He sometimes ended his speeches with "Slava Ukraini" - or "glory to Ukraine".

Johnson even spoke stilted Russian in February, telling the Russian people that he did not believe the "needless and bloody" war was in their name.

Russia repeatedly dismissed him as a poorly prepared jester trying to punch far beyond Britain's true weight.

Zakharova gleefully portrayed Johnson as the author of his own downfall.

"Boris Johnson was hit by a boomerang launched by himself," she said. "His comrades-in-arms turned him in."

Reuters