Italy's prime minister has blamed leftists after a European Parliament committee rejected his conservative nominee for justice commissioner.
Mr Buttiglione also takes a conservative view of marriage
Italian leftists were guilty of "crude propaganda," Silvio Berlusconi said.
The Civil Liberties Committee narrowly rejected Rocco Buttiglione, a Roman Catholic who told an EU hearing last week he thought homosexuality a sin.
The committee's vote is not binding, as the parliament does not have the power to reject individual commissioners.
The rejection of Mr Buttiglione was hailed by Italy's left-wing opposition.
"This is just the latest confirmation of the lack of credibility Italy is subject to in the European institutions because of choices made by Berlusconi," said former Industry
Minister Pierluigi Bersani, a member of the Democrats of the Left.
Sergio Lo Giudice, president of the Italian gay rights group Arcigay, said the vote showed the EU's strong commitment to human rights, including those of gay people.
"We are pleased and reassured by the decision: the Vatican's backyard ends at the Alps," he said.
Observers say the move is an embarrassing setback for the new commission, which is due to take office on 1 November.
The European Parliament's Civil Liberties Committee voted 27 to 26 against the appointment of Mr Buttiglione, the European affairs minister in Mr Berlusconi's government.
They then voted 28 to 25 against Mr Buttiglione's re-appointment to another post within the commission.
However, the European Parliament can only endorse or reject the entire 25-strong team when it votes on 27 October.
Mr Berlusconi described Monday's vote as a "dreadful start" for the new session of the European Parliament.
"It reflects the crude propagandist nature of the personal arguments put
forward by the leftist faction of Italy's parliamentary delegation," he said.
The vote smacked of "fundamentalism if not obscurantism" because it called into "question the freedom of conscience and opinion of a Catholic commissioner, contesting the distinction he makes between morality and the law", the Italian prime minister added.
German conservative MEP Ewa Klamt said the vote against Mr Buttiglione was "discrimination against a man who has a personal religious belief".
"He made it very clear there should be no discrimination for anyone, not for homosexuality, not for race or for religion," she said.
Mr Buttiglione has also said that marriage exists to allow women to have children and be protected by their husbands.