WASHINGTON — Race again played a pivotal role in yesterday's Democratic presidential clashes, as whites in Indiana and North Carolina leaned solidly toward Hillary Rodham Clinton and blacks voted overwhelmingly for Barack Obama, exit polls showed.

Almost half the voters said they were influenced by the focus on Obama's former pastor, the Rev. Jeremiah Wright.

Obama, the Illinois senator battling to become the first black president, again failed to make an appreciable dent in a crucial voting bloc that has consistently eluded him — working-class whites. But he was piecing together a coalition that besides blacks included the young, first-time primary voters, the very liberal and college graduates.

According to preliminary results from the Indiana exit polls and final data from North Carolina, about two-thirds of whites in both states who have not completed college were supporting Clinton, which the New York senator could use to fortify her argument that she would be the stronger Democratic candidate in the November general election. Of 28 states that have held primaries in which she and Obama competed before yesterday, Clinton had prevailed with working-class white voters in 25.

Wright was a looming factor in the voting, with nearly half in each state saying he was important in choosing a candidate. Of that group, seven in 10 in Indiana and six in 10 in North Carolina backed Clinton.

Those discounting him as a factor heavily favored Obama. In North Carolina, Obama got more votes from people saying they discounted the Wright episode than Clinton got from those affected by it, while in Indiana the two groups were about equal in size.

Among whites, eight in 10 in both states who said Wright affected their choice went with Clinton. That was well above the six in 10 whites overall who supported her.

In both states, two-thirds of Clinton's white voters said Wright was important. That compared with eight in 10 white Obama supporters who said Wright was not a factor.

The six in 10 whites in both states supporting Clinton were similar to her margin over Obama among whites nationally so far.

Nine in 10 blacks in both states were backing Obama — a typical margin for him. That proved decisive in North Carolina, where they comprised about a third of voters — double their proportion in Indiana.

Obama and Clinton were running about even among independents, a group he usually wins.

Although Clinton had her usual lead among Catholics in Indiana, she and Obama were dividing them about equally in North Carolina. Obama also had an edge in both states among first-time primary voters, underscoring his continued ability to draw new voters to the polls.

North Carolina was clearly Obama's stronger state, and that showed among many groups of voters. He was leading there among young voters, college graduates and those earning more than $100,000 a year.

Clinton was making a robust showing in Indiana among white men, a group she and Obama have split about evenly but whom she won handily in Pennsylvania and Ohio. She and Obama were about equally dividing the votes in Indiana of whites under age 30 and people earning at least $100,000 a year, groups that usually have leaned toward Obama.

In both states, whites who said race was an important factor were favoring Clinton, as they have before. Older voters were also solidly behind her as usual.

Voters in both states overwhelmingly named the economy as the nation's top issue.

The preliminary results were from exit polling by Edison Media Research and Mitofsky International for The Associated Press and television networks conducted in 35 precincts in each state. The data was based on 1,738 people voting in Indiana's Democratic contest and 2,316 people in North Carolina, with a margin of sampling error of plus or minus 4 percentage points in Indiana and 3 points in North Carolina.