For cooperation between parties to work in our system, the party not in power HAS to accept that the party in power has the right to be and that it has the right to at least try to get its agenda passed.
The Republican Party has refused to accept this about the Democratic party- even in times like the 1993 to 2001 period, when we had a Democratic president who had essentially promised to govern as a Republican - and is clearly not going to accept it about any Democratic president for the rest of eternity- the Republican notion of "bipartisanship" is a Democratic president acting as a powerless, irrelevant junior partner to a Republican Congress. As long as that is the case- and as long as much of the Republican Party has not given up on trying to overturn the last election, it's not going to be possible.