Moderate Democratic Sen. Evan Bayh announced this week he will not seek re-election in November, citing the worse-than-ever partisan divide. The moderate’s decision triggered Democratic fears of a blood bath in the fall, when their losses may go beyond the historic swing toward the opposite party that follows the election of a new president. President Barack Obama may experience what the last Democratic president saw in 1994, when Republicans effectively labeled President Bill Clinton a big-government proponent who wanted to regulate the health care industry and Democrats lost control of both houses of Congress.

The irony is that Mr. Obama ran as a “post-partisan” candidate. If he loses his party’s control of Congress because it has become too partisan, it is a bitter blow to his hope and change agenda.

In a telephone interview with the BDN two years ago, as he prepared to campaign in Maine’s Democratic caucuses, Mr. Obama expressed confidence that he could lead the government away from its partisan divide. He had not been in Washington, D.C. during the Clinton years, he said, years marked by a never-ending cycle of payback for grudges. He may have been naive.

Had George W. Bush relied more on his reputed charm and less on the cut-throat tactics of his adviser Karl Rove, partisan fevers may have cooled. Instead, the Rove doctrine, which aimed for legislative wins even if by one vote, exacerbated the divide.

After early unity, the 9/11 attacks heightened the partisan atmosphere. Every policy debate was seen, often sincerely, as a matter of life and death. One wonders what would have happened if the Bush years had been more like the Eisenhower years, with few international or domestic crises.

Partisanship will not end overnight, Mr. Obama has said. His extraordinary overture of meeting with the GOP Congressional caucus is a step in the right direction.

To some degree, partisanship is exaggerated by the fun-house mirrors of talk radio and preaching-to-the-choir networks like Fox News and MSNBC. Votes in committees often do not follow party lines, but rather break by geography, rural vs. urban, and other parochial concerns.

It’s a long shot, but the two-party standoff would end if another party asserted itself. The Tea Party may provide that impetus, although its recent convention was more of an Obama-bashing festival. Or maybe the Libertarian Party, which saw new life in the presidential candidacy of Ron Paul. The Green Party also could provide a third way.

When the views of Ralph Nader, said to be on the far left, and Pat Buchanan, said to be on the far right, begin to sound harmonious on some issues, it suggests Democrats and Republicans have imposed a two-dimensional view of politics that is not accurate. A viable centrist or other third party could force a sort of parliamentary approach in Congress, creating coalitions and compromise.

The majority-minority dynamic should not be so difficult; the majority party sets the agenda, the minority works to refine the best and trim the worst. Voters must judge the success or failure of their representatives by that measure.