Editor's note: Julian E. Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" published by Times Books and editor of a book assessing former President George W. Bush's administration published by Princeton University Press.
Princeton, New Jersey (CNN) -- In professional football, teams need a good offense if they hope to win the Super Bowl.
While the conventional wisdom used to stipulate that good defense usually wins championships, a recent statistical analysis found that was not true. Fans of the New York Jets have seen this year -- as full disclosure, this author is a longtime follower of Gang Green -- all of the defense in the world can't overcome the damage done when the quarterback, in this case Mark Sanchez, falls flat. When he plays well, the results are impressive.
The same can be said about politics. Being good at defense is important, but you need to play offense to win elections and shape political debate. When parties only respond to criticism and participate in the discussion that their opponents want to have, eventually their team will get tired of just being in a reactive mode and the other side will score points.
Republicans have been very good at playing offense. In his recent memoir, "Decision Points," President Bush reveals very clearly the Republican style. Although he apologizes for particulars, such as the fact that weapons of mass destructions were not found in Iraq and some of his failures in handling the aftermath of Hurricane Katrina, Bush is unapologetic about the overall value of his his policies.
He insists that the war in Iraq made the world safer, even if it greatly damaged the credibility of the nation and his White House. On counterterrorism, Bush recounts that when George Tenet asked if he could use "enhanced interrogation techniques, including waterboarding" on Khalid Sheikh Mohammed, his answer was: "Damn right."
When Republicans were in the congressional minority between 2006 and 2010, they refused to cede ground to the Democrats. While commentators on the left and the right were focused on the fact that public approval ratings for the GOP had fallen to abysmal levels, congressional Republicans continued to champion most of President Bush's policies.
Almost nobody broke ranks, and they kept up their attacks on Democrats. Republicans have remained united in their opposition to President Obama's policies as well, charging that he has undertaken a socialistic experiment by expanding government and criticizing the administration for being left of center.
If one listened to their rhetoric, it was almost as if the 2008 election never happened.
As soon as the 2010 midterms were over, Republicans, though they will only control the House, immediately jumped up to say that this was a mandate for conservatism. They have promised to overturn what Obama had accomplished.
Mitch McConnell, sounding as if he is about to become the Senate majority leader, proclaimed soon after the election that "our primary legislative goals are to repeal and replace the health spending bill, to end the bailouts, cut spending and shrink the size and scope of government, the only way to do all these things is to put someone in the White House who won't veto any of these things."
In recent decades, Democrats have rarely shared this political style, of staying on the offensive regardless of losses suffered. The party seems to live in fear under the shadow of Ronald Reagan. Liberalism is still a dirty word, even to Democrats.
Even when Democrats win elections and control of government, many in the party are reluctant to defend their own agenda, champion their own ideals, and to move forward with confidence and bravado.
From the start of his time in the White House, President Obama has always been on the defensive. He has frequently warned the "professional left" about the difficulties that he faces in the Senate and about the need to placate conservatives. With the stimulus package in 2009, he bargained with himself by starting with a figure that was much lower than many economists thought was necessary to jumpstart the economy.
With health care, the administration made numerous concessions to the health care industry and to a handful of centrist Democrats whose votes were pivotal about cost control and coverage that make the long-term success of the program quite tenuous.
It remains to be seen if the program will be able to curb the cost of insurance premiums. The health law also depends on the cooperation of state governments, many of which are now under Republican control, to make sure that the program works.
In the press conference that followed the midterms, the president did not come out swinging. Instead, he was generally apologetic about what he had done in his first two years, focusing on areas where he could reach agreement with the Republicans.
When asked about government overreach, instead of defending his policies, Obama admitted that Americans had started to look at all of his programs and "felt as if government was getting much more intrusive into people's lives than they were accustomed to. Now, the reason was it was an emergency situation. But I think it's understandable that folks said to themselves, you know, maybe this is the agenda, as opposed to a response to an emergency. And that's something that I think everybody in the White House understood was a danger. We thought it was necessary, but I'm sympathetic to folks who looked at it and said this is looking like potential overreach."
This was a contrast to Bush who after 2006 admitted that he took a "thumping" but went on to say the message was that the "American people want their leaders in Washington to set aside partisan differences, conduct themselves in an ethical manner, and work together to address the challenges facing our nation." He conceded almost nothing on policy.
Rather than defending the legacy of FDR and LBJ, Obama and other Democrats have been waxing nostalgic about President Bill Clinton's policy of "triangulation" where he boosted his approval ratings by co-opting the ideas of the right.
If Democrats once again choose a rallying cry of "the era of big government is over," they are not playing offense. This might result in some short-term gains in the polls--although it didn't work when Obama did this in his first two years -- but over the long run it leaves Republicans to shape the terms of the debate.
There have been some moments in history when Democrats took a different stance.
In his 1964 State of the Union address, nearly a year before his huge landslide victory over Arizona Sen. Barry Goldwater, Lyndon Johnson boasted that: "Let this session of Congress be known as the session which did more for civil rights than the last hundred sessions combined; as the session which enacted the most far-reaching tax cut of our time; as the session which declared all-out war on human poverty and unemployment in these United States; as the session which finally recognized the health needs of all our older citizens; as the session which reformed our tangled transportation and transit policies; as the session which achieved the most effective, efficient foreign aid program ever; and as the session which helped to build more homes, more schools, more libraries, and more hospitals than any single session in the history of our republic."
Even President Clinton learned this lesson after the 1994 midterms. While many commentators have been pointing to his shift to the right after the Republican takeover of Congress, Clinton actually rebounded when he stood up against the Republican's proposed cuts to Medicare and after the bombing in Oklahoma City where he condemned the extremist right for its harsh rhetoric about federal power.
The Democrats might want to take a page from the playbook of the Republican Party. Instead of backing down and running away from their platform, they might instead embrace what the party has stood for and make a case as to why their record is better than what Republicans have to offer. If Democrats can't do this, Republicans will shape the political dialogue in the next two years, regardless of what shifts Obama makes, and Democrats will be looking at a defeat in 2012.
The opinions expressed in this commentary are solely those of Julian E. Zelizer.