IN an interview last week, Hillary Clinton declined to commit to whether she would run for president in 2016, but said she is "certainly in the camp that says we need to break down that highest, hardest glass ceiling in American politics".

To have a woman president is something she would "love to see happen".

Clinton was referring to a previous speech, in which she memorably conceded defeat in the 2008 presidential race by saying that "although we were not able to shatter that highest and hardest glass ceiling this time, thanks to you it has 18 million cracks in it" (referring to the number of votes she received). That the comment was made after she pulled out of the race is significant: Clinton had long been reluctant to "play the gender card", and only began to do so, decrying the sexism she had faced as "deeply offensive to millions of women", when she became more embattled midway through the race.

Last week's comments suggest she is more willing to play the gender card. At one point, in 2007, she was seen as a frontrunner, almost a shoo-in, to be the first woman ever to win the nomination of a major party in US presidential elections. There was an air of certainty then, when she announced: "I'm in and I'm in to win." But what happened the next year, made many wonder how far the United States had really come towards being able to elect a woman as president.

Of course the 2008 presidential race was a matter of race versus gender candidate. We can't say that Clinton lost because the glass was much more impervious to the heads of women knocking-up against it than those of men of any racial background. Was it simply that she was up against Barack Obama, a gifted politician whose message of change resonated more? Or was it that America was still not ready?

Anne Kornblut, in her book Notes From The Cracked Ceiling, examined the campaigns of Clinton and Sarah Palin and observed that there are still formidable obstacles in the way of a woman becoming president. Among them are the difficulties in striking the right balance "between femininity and toughness" and the need to weather stinging gender-based attacks. Let's not forget the lows of 2008: the harsh sexisms meted out by the media on Clinton: radio host Rush Limbaugh asking "Will Americans want to watch a woman get older before their eyes on a daily basis?"; hecklers who shouted: "Iron My Shirt"; the constant references to her as a "bitch"; author Marc Rudov saying that when she speaks, men hear: "Take out the garbage."

Last week, Vladimir Putin saying "maybe weakness is not the worst quality for a woman"; while her apparent toughness has been the issue for many commentators. Another problem, says Kornblut, is that women don't vote for women. As one Clinton strategist estimated she would get 94% of the female vote, this was not the case. In Iowa, the first caucus (which she lost), her support among young women was in the low teens. For younger feminists, the fact that Clinton first became known to them through her husband's philandering was a put-off.

The question of whether Americans are yet willing to vote for women, makes the presidency one of the hardest glass ceilings to crack. Globally, the number of female presidents and prime ministers has grown, quadrupling over each of the past two decades. But, as Farida Jalalzai, author of Shattered, Cracked Or Firmly Intact? Women And The Executive Glass Ceiling Worldwide, says, women are more likely to gain appointment as prime ministers than win presidencies. She notes that most victorious women candidates tend to come from political families.

Jalalzai believes the US ceiling is firmly "intact" and that "very little has changed ... to make Clinton's 2016 prospects seem more likely".

It's disheartening to see that the misogynistic sniping has already begun. When it was announced that her daughter, Chelsea, was to have a baby, there was a torrent of "granny" comments. One New York Post columnist wrote "an open letter to Chelsea Clinton's foetus" in which he suggested the child would be used as a "stage prop".

Elizabeth Warren, another credible Democrat presidential candidate, has been belittled as a "granny" in headlines. As commentator Kathleen Parker put it: "No-one ever said Grandpa Reagan was too old." But women can't win. So restricted is the range of approved female identity that they are always too old, young, tough, weak, sexy or unattractive. There may be 18 million cracks in the glass, but there are still many million undermining, sexist wisecracks out there. And they are helping to keep the glass ceiling intractably in place.