Politics is often likened to a horse race, but this year the most apt sports comparison might be the boxing match. The presidential contest this year is a brutal one.

The news media are frequently lambasted for focusing on the contest and ignoring the substantive issues. But in some ways the contest is one of the issues; voters wonder who is responsible for the brutality of the campaign and who is behaving with greater fairness and dignity. Voters may wish that politics were conducted with the decorum of a tea party and that civil discussion prevailed over attack ads and distortion. But history follows its own rules, and we are at a bitter moment.

There have been bitter moments and vicious campaigns throughout our history. Voters trying to make up their minds must carry out a variety of calculations. They must see through the rhetoric to assess what the candidates actually believe, or if they believe anything beyond themselves. They must consider the methods and language of the candidate to form a judgment about his or her character. They must look at current conditions of the nation and determine within their own minds what the nation requires.

At this stage of the match it is possible to form some judgments about the candidates and the fight they are waging. First, it is apparent that President Obama has drawn some conclusions about the defeat of John Kerry in 2004. That was the campaign when Kerry allowed himself to be undermined by the lies of the swiftboat partisans whose intention was to distort Kerry’s record of service in Vietnam. There is every reason for Obama to be on guard against the sort of attack that did in Kerry, and he has determined that he will not be swiftboated. The millions amassed by unaccountable super PACs mean that Romney partisans are capable of a massive swiftboating effort.

In anticipation of those attacks, Obama began early by pummeling Mitt Romney with attacks about his record as a financier with Bain Capital. There are grounds for questioning Romney’s record: Romney has presented his experience at Bain as a reason for voting for him. Further, the ideological underpinnings of the campaign make Romney’s history as a corporate wheeler-dealer relevant to the economic issues at stake.

Thus, Obama has placed Romney back on his heels, hoping to define the campaign early so it won’t be defined for him by Romney. It is not a polite discussion. Senate Majority Leader Harry Reid has lobbed the accusation that Romney has paid no taxes in recent years, though he offers no evidence and he has been roundly criticized for landing a low blow.

But this is a contest where low blows are likely to be many. Romney has shown early he is willing to make a race-tinged attack, purveying the falsehood that Obama was weakening the work requirement in the welfare program. Stoking resentment about welfare is a tried-and-true Republican tactic going all the way back to Ronald Reagan’s evocation of so-called “welfare queens.” Newt Gingrich tried it in this year’s primary when he called Obama the “food stamp president.”

Both candidates are struggling to define the narrative that will prevail during this year’s campaign. Once a particular story line takes hold it is hard for candidates or their supporters or the media to dislodge it. Four years ago, as the economy was crumbling, the narrative was about change. There was no way John McCain could rise above that story.

This year the question is which accusations will stick. Will it be the charge that Romney is an out-of-touch plutocrat and errand boy for the privileged class and that only Obama can continue the recovery that has been under way for three years? Or will it be the charge that Obama is a big-government, European-style socialist who has failed to return the nation to prosperity?

We can wring our hands at the bloodletting, or we can study the spectacle hoping to glean clues about the democratic choice that awaits us. One thing is already evident: The choice is a clear one.