Today, John Sidney McCain and George W. Bush were one. Bush endorsed McCain at the White House, saying, "John showed incredible courage, strength of character and perseverance in order to get to this moment and that's exactly what we need in a president." If you think Bush is so unpopular that he can't help McCain among conservatives, you're crazy. Hard-core right-wingers, the folks that don't really trust John McCain, love George Bush with an irrational passion. Of course, there's a danger that this endorsement will reinforce the notion that John McCain is running for what is essentially a third Bush term, in terms of both foreign and domestic policy. But the Democrats were going to hammer that point regardless of whether or not McCain made this trip to the Rose Garden.
The two men have a long history, displayed at right courtesy of a Think Progress photo montage.
For more on what John McCain needs to do to shore up the Republican base, see this.
Update: Bush: McCain "is not going to change" my foreign policy.
Update Update: Check out this SNL sketch on McCain swallowing his pride to endorse Bush in 2004.