Republicans who were unable to defeat Roosevelt in four presidential contests exacted posthumous vengeance upon FDR by winning ratification in 1951 of the 22nd amendment to the U.S. Constitution, which guarantees that no person shall be elected to the office of president more than twice.

After this city's Democratic convention, that amendment may be effectively "repealed," because in 2012 Democrat Bill Clinton, his party's only chief executive to have won re-election since FDR, could be said to be running for his third White House term.

To watch President Barack Obama make his first appearance on the Charlotte convention stage there to congratulate and thank Bill Clinton after his speech was to see an expression of admiring awe this observer had never before seen on Obama's face. It was completely understandable, because in less than 45 minutes, the 42nd president had just made a better public case for the Obama administration than the Obama adminstration had made for itself in 45 months.

And a better case than the 44th president would make for himself and his own re-election the next night.

There is an old Marine Corps maxim that states that no duty station is better than the one the Marine just left and none is worse than the one to which the Marine is currently assigned.

The same may be true for presidents. Bill Clinton has rebounded from the dark days following his 12th-hour pardon of fugitive financier and tax cheat Marc Rich, a certified sleazeball who had repudiated his own American citizenship. Eleven years later, after humanitarian work on a global scale, Clinton is that rare American ex-president who is not only favorably regarded by seven out of 10 of his countrymen, but who is the featured guest of honor and star attraction at his party's national conventions.

Ironically, the totally scandal-free Barack Obama seeks the political equivalent of "innocence by association" through sharing the spotlight and the platform with the only U.S. president impeached by the U.S. House in the last 144 years.