In the end, the election may not settle anything.
If the polls are correct — and there's been heated debate about that — President Obama will be re-elected Tuesday. Even if he is, he'll have to face a Republican House that appears to be no warmer to his agenda than it's been for the past two gridlocked years.
But the polls are still so close that Republican Mitt Romney might be elected. If that's the case, it appears he'll have to contend with a Senate that remains under Democratic control.
Senate Majority Leader Harry Reid of Nevada released a pointed statement Friday saying the idea that Senate Democrats will cooperate with Romney is "laughable."
The potential scenarios for continuing divided and divisive government have created anxiety in some political observers that the next two years in Washington will be no more productive than the past two, during which control of Congress has been divided.
Neither candidate nor party appears likely to win the kind of decisive victory that would allow them to set the course for the months and years ahead. "It would mean that the partisan divide in Washington is going to be, if it's possible to imagine, even more stark than it is now," says Gary Bauer, founder of Campaign for Working Families, a conservative political action committee.
A nearly tied election — with a jump ball for president and razor-thin majorities in both houses of Congress — would reset American politics back where they were a dozen years ago, suggests Lara Brown, a political scientist at Villanova University in Pennsylvania.
In 2000, George W. Bush was elected president while losing the popular vote, making that the third presidential election in a row in which no candidate received a majority of the vote. In 2000, the Senate came out exactly tied.
Since that time, one party or the other has been able to gain strength either from external events or the mistakes of the other party, but has not been able to hold onto power for long.
Bush and congressional Republicans gained strength, politically, from the terrorist attacks of Sept. 11, 2001, but squandered that advantage with missteps in Iraq and the response to Hurricane Katrina.
Democrats regained control of Congress in 2006, and Obama won a big victory two years later in the wake of a financial crisis. But after passing major bills addressing health care, banking regulation and economic stimulus, Obama and his party were repudiated in the GOP sweep of 2010.
"This country has for the most part been swinging on a pendulum in reaction to events," Brown says. "We are just in a place where there is no consensus yet."
The lack of consensus is not only in Washington, but among the electorate. Voters call for common-sense bipartisanship, but the country itself is divided along partisan lines — and an election that results in a tie will not alter that dynamic.
"It's a seemingly schizophrenic public," says Princeton University historian Sean Wilentz. "They keep going back and forth, and it's close."
Of course, not everyone is wholly pessimistic about the chances for more cooperation ahead. The prospect of the so-called fiscal cliff — the need for Congress and the president to resolve questions about expiring tax rates and automatic spending cuts — may force a deal that both parties sign off on.
"Potentially, good things can happen," says Jared Bernstein, who served as an economic adviser to Vice President Joe Biden. "[The election] is a pretty expensive investment to get back to the lousy old status quo."
Still, it's difficult for any minority party that believes it could take power two or four years hence to make deals it believes benefit the incumbent party. Instead, the losing party — whichever one it is — may pursue the same strategy as congressional Republicans in recent years, blocking legislation they don't like and denying the president's party further victories.
But breaking the partisan fever may require the party that loses the White House this time to decide it must moderate its message, in order to appeal not just to core supporters, but to a greater share of the electorate.
In recent years, the parties have taken turns mistaking their victories for mandates from the people and then pushing policies that, it turns out, most Americans didn't support. Power will continue to shift back and forth in this way until one of the parties comes up with an agenda that voters will back over the long haul, Brown suggests.
"It's going to continue this way until both parties learn to hold the center," Wilentz says.