Editor's note: Julian Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" (Times Books) and of the new book "Governing America" (Princeton University Press).
Princeton, New Jersey (CNN) -- President Barack Obama's re-election campaign got off to a rocky start with his attacks on Mitt Romney's record at Bain Capital, the private investment fund.
Tapping into themes that Republican Newt Gingrich introduced during the Republican primaries, the Obama team has been attempting to depict Romney as a ruthless venture capitalist whose record in private business proves that he had little concern for creating jobs or improving the lives of average Americans.
But the first few weeks of attacks have backfired. Newark Mayor Cory Booker, a rising star of the Democratic Party, said that he didn't agree with the strategy, calling the ads "nauseating" and defending venture capital. Massachusetts Gov. Deval Patrick made similar statements about private industry, fueling the impression Obama's surrogates were not on the same page as him.
And Thursday, former President Bill Clinton said on CNN that Romney's record in business and as governor was strong. He said, "I don't think we ought to get into the position where we say, 'This is bad work. This is good work.' "
In short, the attacks don't seem to be working, at least thus far. Why? The first reason is that these kinds of ads are tricky for Obama to pull off since they open him up to attack as much as they allow him to inflict wounds on Romney.
It was one thing for Newt Gingrich, a rock-ribbed conservative, to launch this kind of criticism about Romney's record. It was a little like Nixon going to China. Nobody would confuse Gingrich with a left-wing zealot. But Republicans have been accusing Obama of being left of center ever since the campaign of 2008.
When Joe the Plumber confronted Obama over his support for progressive taxation, the terms of the debate were set. By focusing on the theme of Bain Capital, Obama ends up opening himself up to wrongly being depicted as far left by conservatives while the damage to Romney is limited. The second factor is that these attacks go against the significant changes that have taken place in the Democratic Party since the 1980s.
Many Democrats, led by Bill Clinton, worked very hard to shift the party toward the center on economic issues, embracing free market values and privatization in an effort to redefine the party and counteract right-wing attacks. Like it or not, the identity of the party did change. A new generation of Democrats such as Booker and Patrick were full converts, eager to show their market-oriented chops and very reluctant to support a more left-leaning strategy.
The third factor has to do with our campaign finance system. The reality is that neither party will ever really be anti-market, even if its members wanted to, since the titans of private industry play a huge role in financing Republican and Democratic campaigns.
As the prominent California Democrat Jesse Unruh once said, "money is the mother's milk of politics." And much of that money, for Democrats, has come from the very people they are attacking.
Indeed, Wall Street has been very supportive of the Democratic Party, including Obama. In 2008, according to CNNMoney, Obama raised $16 million from Wall Street compared with $9 million amassed by John McCain.
Many Democrats, ranging from the left to the center, know this and are leery about further angering a constituency that is already deeply dissatisfied with the president. At the local level, mayors such as Booker are doubly cautious since they need to court this kind of money for investment in their cities -- and for their own campaigns.
The final factor is that the economy is still in shambles. Obama is playing a high-risk game each time he focuses attention on issues such as unemployment and job growth.
It is one thing to level these kinds of attacks when national economic times are good, but quite another in the current economic environment. When Obama spends a week on attacking Romney's economic record, and the punch line is a dismal jobs report that offers little hope to many Americans, many are left to wonder what exactly the president thinks that he can brag about.
According to the Hill, one former administration official admitted that the release of the job report was an "Oh ---- moment." "There's no sugarcoating this one," said another.
The president will need to adjust his strategy. Without question, negative attacks on Romney will be integral to his campaign and the Obama team will continue to connect Romney to the right in an effort to switch independents toward the blue part of the electoral map.
But if attacks on Romney's record at Bain and as governor of Massachusetts are to define the Democratic campaign, rather than some kind of positive vision about what he will do to change conditions in the next four years, Obama could easily end up alienating many possible supporters and opening the door for Republicans to focus completely in the coming months on the troubled economic state of America.
The opinions expressed in this commentary are solely those of Julian Zelizer.