Fidesz group leader Máté Kocsis said the government must uncover "the political and media corruption network" that the previous US administration financed.
Noting that the prime minister will appoint a government commissioner to uncover attempts by the US to influence domestic affairs, Kocsis said in an interview with public radio on Sunday that Donald Trump's administration had "unmasked the corruption network", showing that money was spent worldwide "to spread extremist, liberal ideology".
"This network has a foothold in Hungary," he said.
US taxpayer money was used to finance "media platforms, fake civil organisations, activists, and demonstrations" opposed to government policy on "migration, gender propaganda, and war", he added.
Kocsis said Hungarian journalists and activists claiming to be part of the civil sphere had influenced public life "in the interests of a foreign state or a capitalist, speculative corporate group". "This is what political corruption really is," he said.
The sovereignty protection office, he said, was independent of the government. When it came to fully understanding the extent of "the corruption network", however, "the state and government must first conduct fact-finding work" bilaterally, he added.
A government representative will travel to the US to gather relevant data, "because what's reported in the press today is only a fraction" of the totality of what took place.
Kocsis also said that millions of euros from Brussels was used to finance self-proclaimed independent media and organisations that were in fact liberal activists, and similar efforts would be made to uncover the full extent of such activities.
Related legislation will dominate the spring session of parliament, he said, adding that a law similar to the US Magnitsky Act would be tabled, and "everything must be coupled with an amendment to the Criminal Code".
Kocsis insisted that "the liberal elite in Brussels" would launch proceedings against Hungary whatever the case, saying that relations were now at a point "where it doesn't matter what they think".
He said the "wind is blowing from the United States", and this meant sovereignty protection and strengthening nation states.
Commenting on plans to require MEPs to declare their assets in Hungary, he said "everyone who exercises public power in the Hungarian or European parliaments by proxy of Hungarian voters" should abide by the country's transparency requirements.
Asset declaration rules for MEPs were, he said, "very lax" and "opaque" so as to "cover up the corruption cases of the Western elite". Those for MEPs therefore should be the same as the rules for Hungarian MPs, he said, adding that the new legislation would cover"Hungarian citizens".