It is said that Rangel very much wanted to be on the podium with the party's big names, but those in power apparently decided the Congressman wasn't needed.
The main problem, of course, is that Rangel was one of Senator Hillary Clinton's staunchest supporters during the campaign for the Democratic nomination, a campaign in which Hillary and her husband Bill were involved in heated back-and-forth accusations with Obama, including charges of race baiting.
Many blacks are resentful that Rangel and other Harlem politicians chose to stay with Hillary Clinton, even when it became clear that Obama was on course to become the nation's first serious African-American candidate for the presidency.
On the other hand, there are those who think Obama should have allowed Rangel to have a prominent role at the upcoming Convention, even out of self interest, given that Rangel is chair of the very powerful House Ways and Means Committee.
But Rangel has been weakened somewhat, at least superficially, by recent New York Times reports that he had several rent-controlled apartments at the Lenox Terrace apartment complex, at a time when many of his constituents are struggling to find affordable housing.
A miffed Rangel may not remain in Denver for the full four days of the Convention.