He has ticked off liberals in his own party, but itís unlikely that anybody on the left is going to run against him ó particularly, one veteran Democratic guru told me, because it would mean trying to defeat the nationís first African-American president.
A significant challenge in an incumbent presidentís party is one of the classic harbingers of defeat ó one of American University professor Allan Lichtmanís famous ď13 keysĒ to the presidency.
Another, though, is waging an unpopular war or either scoring a major foreign policy victory or defeat. Afghanistan is unpopular and certainly represents a threat to Obama, who has no prospects of a foreign policy triumph.
The major factors, however, will be the economy and the quality of the GOP candidate.
President Ronald Reaganís popularity was at 41 percent in 1982 when unemployment was at 9.7 percent, but he got triumphantly re-elected by bringing it down to 7 percent in 1984.
Clinton was at 42 percent with unemployment at 6.1 percent in 1994 and got re-elected with it at 5 percent.
President Jimmy Carter had a 50 percent approval rating in 1978 with unemployment at 6.1 percent. He was defeated when it was up to 7.1 percent ó and amid the Iran hostage crisis, of course.
President George H.W. Bush had a 58 percent approval rating in 1990 with unemployment at 5.6 percent. He was defeated when it went up to 7.5 percent.
Obama is in treacherous territory with unemployment at 9.8 percent. His administration is forecasting improving that to only 8.5 percent by 2012. He had best do better than that.
Meantime, the latest Wall Street Journal/NBC poll indicates that Obama would beat former Alaska Gov. Sarah Palin (R) 55 percent to 33 percent but outpolls former Massachusetts Gov. Mitt Romney (R) 47 to 40.
The message is that the GOP needs to nominate someone who can appeal to independent voters in order to defeat Obama, and not a right-wing ideologue.
Thatís also the key to an Obama victory ó winning back the independents who supported him in 2008, but voted Republican in 2010.
The way to do that is to go back to the national unity theme he enunciated in 2008 ó but this time, show he means it.
Former Sen. Scott Brown, R-Mass., candidate for U.S. Senate in New Hampshire, holds his hand over his heart during the singing of the national anthem as he waits to take the stage for his town hall campaign rally with Sen. John McCain at the Pinkerton Academy in Derry, N.H., on Monday, Aug. 18, 2014.