Throughout the primary campaign, Barack Obama has avoided going negative on Hillary Clinton, apparently thinking that it would conflict with the “hope” and “change” messages the campaign was built on, but it now looks like things may be about to change:
CHICAGO — Senator Barack Obama woke up on Wednesday talking of his delegate lead and of taking the fight to Senator Hillary Rodham Clinton. But after defeats in two of the most populous states, he also sounded like a chastened candidate in search of his lost moment.
lying from Texas back home to Chicago on Wednesday morning, Mr. Obama delivered the message that he intended to counterpunch forcefully.
His campaign aides on Wednesday urged Mrs. Clinton to release her tax returns from 2006, as well as her papers from her years as first lady, which Mr. Obama’s chief strategist, David Axelrod, described as “secreted in the Clinton library.”
“She’s made the argument that she’s thoroughly vetted, in contrast to me,” Mr. Obama said to reporters aboard his campaign plane. “I think it’s important to examine that argument.”
Over the last year, though, Mr. Obama has struggled to deliver that examination. He picks up the cudgel, and then sets it down. The problem is that Mr. Obama has built a campaign persona as the man of hope, a young candidate with oratorical skills who promises to build bridges across the ideological divide.
If he indulges his inner Chicago pol, formed in a city where politics is conducted with crowbars, he risks taking the shine off. But his advisers say he has little choice.
For example, here’s the memo his campaign released on the tax return issue:
In the face of her unwillingness to release her tax returns, Hillary Clinton has made the false case in this campaign that she is more electable because she has been fully vetted. When it comes to her personal finances, Senator Clinton’s refusal to release her taxes returns denies the media and the American people the opportunity to even begin that process. Though her campaign has tried to kick the issue down the road, Democratic voters deserve to know, right now, why it is she is hiding the information in her tax returns from last year.
(…)
Senator Clinton has also claimed that she is too “busy” to release her tax returns. Given the fact she is able to loan her campaign $5 million, you would think the Clintons would be able to hire an accountant. The reality is that she wants to keep this information hidden from voters. The people of Wyoming, Mississippi, Pennsylvania and the rest of the country should wonder why.
Or this on the experience issue:
Mr. Obama took aim on Wednesday at Mrs. Clinton’s claim that she is a seasoned hand in foreign policy. “What exactly is this foreign experience that she’s claiming?” he said. “I know she talks about visiting 80 countries. It is not clear. Was she negotiating treaties or agreements or was she handling crises during this period of time?
“My sense is the answer’s no.”
Barack Obama’s biggest problem in this campaign has been the fact that he’s never been able to deliver the final blow that would knock Clinton out of the race. He had a chance in New Hampshire and she pulled off a victory. He had a chance on Super Tuesday but Clinton managed to pull of enough wins to make a case for staying in the race. And, finally, he wasn’t able to hold onto a lead in Texas or gain one in Ohio.
If he’s going to beat her, he’s going to have to up the pressure on the campaign. And that means going negative and questioning her viability as a candidate in the General Election. And, you know, she’s a Clinton. There’s more than enough to work with.

[...] I take this as a sign that the Obama campaign’s new tougher strategy may be hitting a few sensitive spots. [...]