WINSTON-SALEM, N.C.  Senator Barack Obama broke forcefully on Tuesday with his former pastor, the Rev. Jeremiah A. Wright Jr., in an effort to curtail a drama of race, values, patriotism and betrayal that has enveloped his presidential candidacy at a critical juncture.

At a news conference here, Mr. Obama denounced remarks Mr. Wright made in a series of televised appearances over the last several days. In the appearances, Mr. Wright has suggested that the United States was attacked because it engaged in terrorism on other people and that the government was capable of having used the AIDS virus to commit genocide against minorities. His remarks also cast Louis Farrakhan, the leader of the Nation of Islam, in a positive light.

In tones sharply different from those Mr. Obama used on Monday, when he blamed the news media and his rivals for focusing on Mr. Wright, and far harsher than those he used in his speech on race in Philadelphia last month, Mr. Obama tried to cut all his ties to  and to discredit  Mr. Wright, the man who presided at Mr. Obama’s wedding and baptized his two daughters.

“His comments were not only divisive and destructive, but I believe that they end up giving comfort to those who prey on hate, and I believe that they do not portray accurately the perspective of the black church,” Mr. Obama said, his voice welling with anger. “They certainly don’t portray accurately my values and beliefs.”