"These are difficult issues and we have seen that in this campaign. Race and gender are difficult issues. And therefore we need to have more discussion about them," she said.
Clinton picked up an endorsement from Pennsylvania Republican John Murtha, a leading congressional opponent of the war in Iraq. Murtha said Clinton was best placed to deal with the issues surrounding the war and the economy.
As the Democrats' battled it out, Arizona Senator McCain was holding his own in a CNN/Opinion Research Corp poll reflecting hypothetical matchups. Obama led McCain by two percentage points and Clinton led him by one.
McCain, who was on a Middle East and Europe swing, said in Jordan that a US troop build-up in Iraq is succeeding and that a premature withdrawal would dramatically enhance Iran's influence in the region.
The Obama campaign is worried the uproar over the pastor's comments could cost him support with white voters in states like Pennsylvania, which holds an important voting contest on April 22.
A Quinnipiac University poll gave Clinton a lead over Obama of 53 to 41 percent in Pennsylvania, compared to a 49 percent to 43 percent lead over him in late February in that state.
"Did I know him to be an occasionally fierce critic of American domestic and foreign policy? Of course. Did I ever hear him make remarks that could be considered controversial while I sat in church? Yes. Did I strongly disagree with many of his political views? Absolutely," Obama said of Wright.
The Wright comments have threatened to overshadow Obama's central message that he would bridge divisions in the United States, including those involving race.
Last week, Geraldine Ferraro, a Clinton supporter and 1984 vice presidential candidate, attributed Obama's lead in the Democratic race to his being black.
Obama said the race discussion took a divisive turn when it was implied "my candidacy is somehow an exercise in affirmative action; that it's based solely on the desire of wide-eyed liberals to purchase racial reconciliation on the cheap."
Blacks took offense when Clinton's husband, former President Bill Clinton, in January compared Obama's victory in the South Carolina primary to success there by Jesse Jackson, a black candidate who ran for president in 1984 and 1988. Critics saw the remarks as a bid to marginalize Obama as a candidate only for black America.
But Bill Clinton told television interviewers on Monday it was a "myth" that his wife's campaign had engaged in racial politics in the Southern state where he said he "never said a bad word about Senator Obama - not one."
In his speech, Obama clearly disagreed.
"We saw racial tensions bubble to the surface during the week before the South Carolina primary," he said.
