A European Parliament committee has narrowly voted to oppose Italian Rocco Buttiglione as the EU's next justice commissioner, officials say.
Rocco Buttiglione considers homosexuality a sin
Mr Buttiglione outraged some members of parliament when questioned about his views on homosexuality and women.
The verdict of the Civil Liberties Committee is not binding. But observers say it is an embarrassing setback for the new commission.
Mr Buttiglione is due to take office at the commission on 1 November.
Jean-Louis Bourlanges, a French liberal MEP in charge of the EU's parliamentary committees, said the verdict "signifies the refusal of the nomination of Mr Buttiglione".
The Civil Liberties Committee voted 27 to 26 against the appointment of Mr Buttiglione, Italy's European Affairs Minister.
They then voted 28 to 25 against Mr Buttiglione's re-appointment to another post within the commission.
However, the European Parliament does not have the power to veto individual members of the commission and can only endorse or reject the entire 25-strong team.
The parliament will vote on the new commission on 27 October.
Correspondents say Mr Buttiglione's views on issues such as homosexuality, which he considers a sin, have prompted unease at the commission.
A devout Roman Catholic said to be close to the Pope, he has also expressed strong opinions on the role of women in modern society.
"The family exists in order to allow women to have children and to have the protection of a male who takes care of them," he said.
"This is the traditional vision of marriage that I defend."
He has also said that the reason behind the low birth rate in Europe was that women were concentrating too much on their careers and not enough on having babies.
The parliament's president, Josep Borrel, has described some of Mr Buttiglione's comments as shocking, saying that perhaps if he were in charge of beetroots it would not be so serious.
Johannes Swoboda, an Austrian social democrat influential in marshalling opposition to the appointment, said the nominee's views may take on political significance.
"Mr Buttiglione made it clear that his private opinions will influence the way he will handle the portfolio," he told the BBC's Europe Today programme.
"This is a very sensitive portfolio which is dealing with discrimination and non-discrimination.
"A man who openly discriminates against homosexuals and who is openly for reducing the role of women cannot deal with these affairs in the commission," he added.
But German conservative MEP Eva Klampt denied that Mr Buttiglione would let his personal beliefs influence his policy-making.
"I believe he is the right man for the right job. This is really 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."