David Broder’s latest homage to the holy temple of bipartisanship, graces today’s WashPost with the sentiment that we’ll be better off if President Obama listens not to those who tell him that bipartisanship won’t work, but to Mr. Broder, who knows, that if he just thinks happy thoughts and claps his hands, bipartisanship will solve all our problems.

Broder notes that Harry Truman succeeded with a Republican Congress to implement the Marshall Plan, and that Lyndon Johnson allied himself with Sen. Everett Dirksen, a Republican, to pass civil rights legislation — just two examples of what” Broder nation” would look like.

These are, of course, great examples of bipartisanship. And, at the same time, they point up perfectly why President Obama won’t be able to follow their example in the foreseeable  future.

When Harry Truman and Lyndon Johnson were working their magic, the Republican party was a pretty heterogeneous organization, made up of pro-business but otherwise liberal or moderate Northeastern lawmakers, socially conservative but somewhat populist midwesterners, and a smattering of constitutional purists and others. Think Dirksen, Percy, Brooke, Rockefeller, Lindsay, etc. The true believers, the arch conservative, states-rights, obstructionist filibusterers were Democrats from the south.

To pass anything resembling progressive legislation required a coalition of progressive Republicans and Democrats to unite against the great southern conservatve Democratic block — especially in the Senate, but also in the House where those same long-serving gents held most of the positions of power by seniority. Almost by definition, in these circumstances, every piece of significant legislation had to be bipartisan.

The situation today? The GOP is monolithic. It has driven out anything even resembling nonconformity. In Congress, the GOP votes as a solid block in whatever way a small group of ideologues order it to vote. The obstructionist southern Democrats of yore simply switched parties and drove out anyone who disagreed with them.

Far from being the liberal party they’re frequently portrayed to be, Democrats now include many who in another era would be Republicans — pro-business, pro-civil rights, moderates and balanced-budget conservatives, for example.

Mr. Broder, please note: Any legislation that gets a large majority of Democratic Party members’ support IS bipartisan in the sense that you’re recalling with regard to Truman and Johnson. The problem is that, for now, the ideologues and obstructionists have gathered in the GOP corner and sent all the moderates to the other side of the room.

In this climate, President Obama already has won a major bipartisan victory.