With thousands of protesters expected on the streets of Brussel's on Monday to greet the US president - his first trip since re-election - both the far left and far right had already gained a head start.
Hundreds of skinheads and communists demonstrated on Sunday, with the right wanting Bush to pull US troops out of Europe and the left criticising what they saw as the US president's disdain for international law.
Bush is due to meet Belgian leaders on Monday and European Union and Nato leaders on Tuesday to talk about Iran, Syria and Iraq as well as Nato's future.
More protests are expected over the coming days with environmental, human-rights and peace groups, the far left, socialists and anti-globalists all planning to take to the streets.
Several hundred left-wing demonstrators gathered in the historical heart of Brussels - home to Nato and the EU - to criticise Bush for not signing up to the Kyoto treaty to tackle global warming and for the US-led war in Iraq.
One demonstrator carried a flag with a Nazi swastika sign woven into a US flag, while the front page of a communist weekly had an image of the famous Brussels Manneken Pis statue urinating on Bush's head. Other protesters held communist flags
"I am protesting against Bush's visit and the fact that [huge] security is being funded by the Belgian taxpayer"
Tom, Belgian social worker
. "I am protesting against Bush's visit and the fact that security is being funded by the Belgian taxpayer. That's inappropriate for such a criminal," 25-year-old Tom, a social worker, said.
Outside the US embassy, several dozens of nationalist right-wing demonstrators, some of them skinheads, demanded US
troops to pull out of Europe.
"The Cold War is over. Nato no longer has any purpose," Dirk, a 25-year old student said.