A poll conducted immediately following presidential contender Mitt Romney's faith speech last week found that about one out of six Americans still say they would not support their party's nominee if that person was a Mormon.

Seventeen per cent of Americans, including similar proportions of Republicans and Democrats, responded they were unwilling to vote for a Mormon presidential candidate even if the person was "generally well-qualified" for the position, according to The Gallup Poll released Tuesday.

The December 6-9 survey showed that Americans' opinions on voting for a Mormon candidate for president has changed little since this question was asked by Gallup in 1967.

Four decades ago when Romney's father - former Michigan Governor George Romney - was seeking the presidency, 17 per cent of Americans had also said they would not support a Mormon as their party's nominee for president.

Likewise in 1999, 17 per cent of respondents expressed unwillingness to vote for a Mormon for president.

But opposition to a Mormon presidential candidate has decreased since the beginning of this year.

In early February, before Romney first officially declared his candidacy, the percentage opposed to the party's nomination of a Mormon was 24 per cent. The statistic dropped to 19 per cent in March, after he entered the race.

An August Gallup poll, meanwhile, showed 22 per cent of Americans think being Mormon is an "undesirable" characteristic for the next president.

Last Thursday, Romney delivered a much-anticipated speech on "Faith in America", partly aiming to reassure evangelical voters who are suspicious of Mormonism. The speech, which he had put off giving for months, was also likely delivered in response to former Arkansas Governor Mike Huckabee's sudden lead in Iowa caucus polls. Romney had been leading in Iowa for months.

Although Romney may have cared more about his speech's impact on conservative Republicans, the latest Gallup poll shows that it had the same effect whether the listener was Republican or Democrat.

Even after the speech, the poll suggests attitudes have changed little despite the candidate's effort to address concerns on how Mormonism would affect his decisions as president.

Eighteen per cent of both groups say they would not vote for a Mormon, similar to the 20 per cent to 21 per cent who gave the same response in March.

A February 2007 Gallup poll, however, showed Republicans were more opposed to voting for a Mormon candidate. Thirty per cent of Republicans compared to 23 per cent of Democrats expressed opposition.

Gallup concluded: "Up to 14 per cent of Republicans have supported Romney for his party's nomination at various times since June 2007. Still, he clearly faces some anti-Mormon opposition to his candidacy within the Republican Party as well as among the general public."

The Gallup Poll also found additional biases potentially harmful to other candidates from both major parties. Four per cent of Americans (including 3 per cent Republicans) say they would not vote for a Catholic; 5 per cent would not vote for a black person; 12 per cent would not vote for a woman; and 12 per cent would not vote for a Hispanic.

In addition, in a Gallup poll earlier this year 28 per cent of Americans said they would not vote for someone who is on his third marriage, and 40 per cent would not vote for someone who is 72 years of age.

Results from the latest survey are based on telephone interviews conducted 6 - 9 December 2007, with 1,027 national adults, aged 18 and older.