In a way, I have come to blame myself for believing that Mr. Bush could be a uniter and not a divider. In retrospect, it is clear that he was a divider in Texas, too. Even while working with Democrats, he destroyed the Democratic Party here with his personality.  When Mr. Bush announced his candidacy for governor against Ann Richards in 1993, Democrats dominated the statewide offices and held majorities in both houses of the Legislature. When he left for Washington, they held no statewide offices, had lost control of the Senate, and would soon lose control of the House. He did it through his personal popularity, which was so great that Democrats didn’t dare to be Democrats, and soon there were few Democrats to speak of, except African-Americans and Hispanics. To this day, the party has not recovered.  Mr. Bush’s claim to have governed Texas in a bipartisan spirit was based on his record of cooperation with Democratic legislative leaders. And the good will was genuine. The leadership embraced his proposals and Governor Bush didn’t meddle with the usual legislative initiatives, including the state budget.  As a presidential candidate, Mr. Bush warned Tom DeLay and other Congressional leaders not to balance the budget on the backs of the poor. After his inauguration, he received considerable Democratic support for his response to the 9/11 attacks, for the Patriot Act and for the No Child Left Behind law. But in the second year of his presidency, the notion of Mr. Bush as a uniter soon receded from memory.  The president campaigned vigorously during the 2002 elections to help Republicans regain control of the Senate. Differences over fundamental issues like the war in Iraq and the confirmation of judges prevented a rapprochement between the president and the Democrats, which, by the time Mr. Bush won a second term in 2004, neither party really wanted.  In a multiparty parliamentary system, a deft leader can form, dissolve and reorganize governing coalitions, but in the American political system, the imperative of the majority is to hold power and the imperative of the minority is to seize power for itself. It may serve the minority’s interest to cooperate from time to time, but in principle it can advance itself only by opposing the majority.  In a world of bloggers and talk radio and 24/7 news cycles, Mr. Obama — or anyone else who goes into politics — is making promises he can’t keep when he says he wants to work with the other side. Yes, there are moments when politicians look to the common good and when both sides conclude that compromise is in their best interest. In general, however, the nature of American politics is, and should be, adversarial.  For many liberals and independents, the lesson of compassionate conservatism and the Bush presidency has been that policy matters more than campaign rhetoric. Conservatives who are drawn to Mr. Obama’s politics of hope would be wise to remember that.  Paul Burka is the senior executive editor of Texas Monthly.  A version of this op-ed appears in print on , on Page A15 of the New York edition with the headline: United We Fall. Today's Paper|Subscribe
Just as President Bush failed to unite Washington, so Barack Obama will have to accept that conflict, rather than unity, is the natural condition of politics.