Though McCain has split with Bush on critical policy issues -- like campaign finance reform and the treatment of detainees -- the president said he would help McCain if he became the GOP presidential nominee.

CNN: McCain gets mixed message; Dems deadlocked after contests

Americans were evenly split on whether Bush is "competent, " with 47 percent saying yes, 47 percent saying no and 6 percent expressing no opinion.

CNN: Bush's approval ratings slide to new low

The Republican Party still contains competing establishment and reform factions, most recently seen in the factional split between George W. Bush and John McCain in 2000.

CNN: What we in 2012 can learn from Teddy Roosevelt in 1912