President Barack Obama has asked NAACP members to keep standing with him as he seeks re-election and sells his message of helping the middle class.

Obama appeared in a taped video message at the civil rights organization's convention in Houston on Thursday.

The nation's first black president told the National Association for the Advancement of Colored People that he stands "on your shoulders." He didn't mention Republican rival, Mitt Romney, who addressed the convention on Wednesday.

Romney told the group he would do more for African-Americans than Obama has.

Neither the White House nor Obama's campaign had indicated Obama would appear by video. Obama's campaign had said he could not appear in person because of a scheduling conflict.

Meanwhile,
Vice President Joe Biden is rallying support for President Barack Obama by telling the NAACP that Obama has the "character of his convictions."

Biden drew cheers as he credited Obama for championing a landmark health care law and launching the mission that killed al-Qaida leader Osama bin Laden.

The vice president outlined detailed differences between Obama and Republican rival Mitt Romney on health care, education, energy, women's rights and research.

Members of the civil rights organization, gathered for their annual convention, offered a rousing reception one day after jeering Romney at times during his speech.