Hungarian Prime Minister Viktor Orban will host dozens of European leaders in Budapest later this week boosted by his "dear friend" Donald Trump's US election victory, but with relations with other EU states increasingly strained.

Europe will need to rethink its support of Ukraine if Donald Trump is elected president of the United States, Hungarian Prime Minister Viktor Orban said on Sunday, as the continent "will not be able to bear the burdens of the war alone".

The upstart political party that launched a challenge against Hungarian Prime Minister Viktor Orban’s rule only months ago has extended its lead against the nationalist leader in the latest opinion poll on Tuesday.

Hungarian Prime Minister Viktor Orban is due to host dozens of European leaders in Budapest later this week as relations with fellow partners have become increasingly strained.