By Jon Donnison
BBC News, Washington
The "fighting Irish" is the nickname for sporting teams at Notre Dame, one of America's largest Catholic universities.
Mr Obama's visit to Notre Dame could spark protests
When President Obama gives a speech there on Sunday, the man who was elected promising to bring an end to the so called "culture wars" will be hoping his views on abortion do not re-ignite hostilities.
The president is due to give what is known in America as a "commencement speech", but in terms of his popularity he will want it to be a question of more of the same rather than any kind of new beginning.
The president will address thousands of Notre Dame students at their graduation ceremony.
Such speeches are usually not controversial. Indeed, Mr Obama has already given several at other universities around the country this week, sticking to the safer ground of joking about the relevant college sports teams and trying to inspire America's brightest and best as they step out into the jobs market during one of the bleakest economic periods in US history.
But on Sunday, he might have to touch on more sensitive issues.
Not all Notre Dame students are Catholic by any means, but a good proportion of them are.
And the president's views in support of abortion rights have upset some of them.
When he steps up to give his address, at the university's Indiana campus, he will be greeted by the pomp and ceremony of Hail to the Chief, the traditional song that is usually played whenever the president arrives at an event.
But in the run-up to this speech, the mood music has had a more sinister tone. Anti-abortion campaigners have been running TV and online adverts backed by dramatic music and Hollywood thriller-style scripting, urging people around the country to protest at Mr Obama's speech.
CATHOLICS IN AMERICA
60 million Catholics in US
49% think abortion should be legal in most or all cases, against 42% who think it should be illegal
50% think it was right to invite Mr Obama to give the Notre Dame speech; 28% think it was wrong
"It's clear that Notre Dame didn't understand what it means to be Catholic when they issued this invitation" the online advert says.
In the town of Notre Dame, where the University is based, demonstrators carrying placards have been protesting all week.
One placard read: "Would you invite Pilate after he condemned Christ?"
Catholic bishops across the country have strongly criticised the university's President - Reverend John Jenkins - for inviting Mr Obama. Some have called for him to be sacked.
And conservative Republicans are trying to use the Notre Dame event to get the right to rally around a cause. Former Speaker of the House Newt Gingrich is one of them.
Mr Gingrich, who recently converted to Catholicism (despite being thrice married and twice divorced), has called for people to organise "Nationwide Prayer Meetings to Protect the Unborn" at the exact time the president is giving his speech.
But such opinions are by no means uniform, among Catholics at Notre Dame or nationally.
There are over 60 million Catholics in the US, but polling from the Pew Research Forum suggests 49% of them think abortion should be legal in most or all cases, compared to 42% who think it should be illegal in most or all cases. The figures for the population as a whole are almost identical.
Other Christian denominations are far more opposed to abortion; 70% of white evangelical Protestants, for example, think abortion should be illegal in most or all cases.
Half of Catholics nationally think it was right to invite Mr Obama to give the Notre Dame speech, while only 28% think it was wrong.
And the make-up of the Catholic Church is changing. About a third of all Catholics in America are now Hispanic, an ethnic group that voted overwhelmingly in favour of Mr Obama in the 2008 presidential elections. Sixty-six per cent of Hispanics voted for Mr Obama compared to only 32% for John McCain.
Abortion is still a divisive issue in America, but not to the same extent that it was when George W Bush was elected in 2000.
Figures from the Pew Forum indicate that abortion was not even in the top 10 most important issues for voters in 2008.
It fell way behind the economy, jobs, healthcare, energy and war in Iraq.
President Obama will not want Sunday's speech at Notre Dame to change that.
America's only ever Catholic President, John F Kennedy, gave a famous speech while running for election in 1960 urging people not to vote for or against him because of his faith.
He argued that there were more pressing issues than religion for the country to deal with.
Almost half a century on, President Obama, his Christian faith notwithstanding, may well feel the same.
Some observers here feel if he is able to give a calm and conciliatory speech, the anti-abortion protesters could make him look like the voice of moderation, while they are left rallying on the fringes.