He has been portrayed as the “acceptable” Republican candidate, the person the party establishment could gather around to halt the advance of either Donald Trump or Ted Cruz.

But on Saturday, Marco Rubio found himself at the centre of fresh controversy when he adopted the most hardline position of the any of the Republican candidates on the issue of abortion. The 44-year-old Florida senator said he would not make exceptions on the issue of abortion for either rape or incest, and only supported such procedures if a woman’s life was in danger.

“I want to be frank,” Mr Rubio told the New Hampshire audience at Saturday night's Republican debate. “I would rather lose an election than be wrong on the issue of life.”

Mr Rubio, who came third in the recent vote in Iowa and whose campaigning skills and photogenic charm have led many pundits to predict he will become the establishment candidate given the failure of Jeb Bush to energise voters, went as far as to claim that the Democrats were on the fringe on this issue, not him.

“On abortion the Democrats are extremists,” Mr Rubio. “Why doesn't the media ask Hillary Clinton why she believes that all abortions should be legal, even on the due date of that unborn child?”

Mr Rubio’s position places him to the right of either Texas senator, an evangelical Christian, Mr Bush and Chris Christie, who both claim to be “pro-life”, but would permit abortions for incest and rape. Mr Trump also supports the "exceptions".

New Hampshire explainer

On Sunday morning, Mr Rubio’s campaign issued a press release claiming that his comments on Saturday night’s debate - where many observers believe he fared poorly - had been his defining moment. One of his advisors said on Twitter that the campaign had received a huge surge afterwards in donations.

“This week the other candidates made one thing clear: They were going to try and take out Marco tonight. They failed,” it said.

“Marco stood up for his principles, he demonstrated his deep understanding of the issues, laid out his record of accomplishment, and made the case for why he’s the conservative who can beat Hillary Clinton.

At at an event in Londonderry high school, some of those gathered said they supported Mr Rubio's position. "He advocated for innocent life. It takes a lot of courage to stick to your views," said Robert McCarthy, a lawyer from Boston who had come with his family.

Others said they were more attracted by what they called the senator's calm manner. "He just seems more mature than the others," said Mary Kay, who works as a medical records clerk.

“One of the best moments: When asked about his position on abortion, Marco laid out why he thinks it’s not a political issue, it’s a human rights issue, and why all life is worthy of the protection of our laws.”

Todd Harris, an advisor to Mr Rubio’s campaign, said on social media: “We raised 3X as much money during this debate as we have during any previous debate.”

Senator Lindsey Graham, who dropped out of the Republican race, said that Democrats would use Mr Rubio’s comments to attack him. He said the senator’s position was similar to that of Republicans Todd Akin of Missouri and Richard Mourdock of Indiana, who lost Senate races in 2012 because of gaffes over their hardline abortion positions.

“I’m pro-life. The most tragic thing in the world is for a woman to be raped, a child, a pregnancy caused by rape,” he told CNN.