BUDAPEST, Hungary — One day after Viktor Orban and his governing Fidesz party and its allies won a sweeping election victory, independent election monitors said Monday that the party had used the resources of the state on a very large scale to bolster its chances of winning.

“Voters had a wide range of political options, but intimidating and xenophobic rhetoric, media bias, and opaque campaign financing constricted the space for genuine political debate,” said Douglas Wake, the head of the Organization for Security and Cooperation in Europe, or O.S.C.E., mission in Hungary.

“The ubiquitous overlap between government information and ruling coalition campaigns, and other abuses of administrative resources blurred the line between state and party,” he said.

The blurring of the line was visible on thousands of bus stops, billboards and telephone booths where the government plastered posters warning of the dangers of immigrants. They were paid for by the government as part of what it said was a public information education campaign.