There are fears they do not have the 21 votes needed to pass it.
The poll from Rutgers-Eagleton surveyed 903 people in early November, asking them about their religious beliefs and views on marriage equality.
Among Catholics, 48 per cent supported gay marriage, while 40 per cent opposed it and 12 per cent were undecided.
Protestants held the opposite view, with only 34 percent supporting and 55 percent opposing gay marriage, and 11 per cent undecided.
Jewish respondents supported gay marriage 56 per cent to 40 per cent and four per cent undecided, while those with no preference are the most supportive, at 85 per cent to only ten per cent opposed with five per cent undecided.
David Redlawsk, director of the Rutgers-Eagleton Poll and professor of political science at Rutgers University, said: “As with several social issues, many Catholics support a more liberal public policy than does the church itself... Read complete article & more - By Jessica Geen -> pinknews.co.uk