One of the more interesting trends in this year's Democratic primaries has been that Obama closes very well. By that we mean that polls in the various state races usually show that Obama gains on Clinton the closer they get to an election. Ohio is no exception to this trend. Polls show that Clinton still has a significant lead in Ohio, but that Obama is narrowing the gap as the campaign gets closer to the March 4 election.
Our take on this is that a lot of journalists don't understand how important name recognition is in political campaigns. Journalists, especially political journalists, are very knowledgable about candidates running for political office. They have to be, it's their job. Not only is it their job, it is also their passion. For most voters, however, politics is not their job and not their passion. Therefore they don't follow politics very closely, if they follow it at all.
This means that Clinton's support was always softer than most reporters realized. Once there was only one main opponent for the media to concentrate on, she faced the prospect of losing support because that opponent would become better known and therefore voters would be more comfortable voting for such an opponent.
What she probably didn't see happening was that the main opponent would be Barack Obama and not one of the white guys who were running. Barack Obama had the potential of getting support from a significant group of voters inside the Democratic Party because of his race, just like Clinton had the potential of getting support from voters because of her sex.
The problem for Clinton, however, is that women, including white women, are much more divided about her than African-American voters are about Obama. One reason for this is her vote for the Iraq War resolution in 2002. In 2004 Howard Dean got a lot of support from Democrats upset about the Iraq War, but couldn't close the deal. The war wasn't yet recognized as the disaster it has turned out to be and Dean didn't have Obama's political communication skills.
If Clinton was running against a white male candidate who had supported the 2003 Iraq War resolution, then she would be winning the Democratic nomination. Unfortunately for her, her main opponent has turned out to be a charismatic African-American politician who opposed this war from the beginning. The better Democratic voters know him, the more comfortable they are voting for him. That's why Obama closes well, and that's why Clinton is fighting for her political life as a presidential candidate in Ohio and Texas.