The differing situations for the Republicans and Democrats have clear implications for both parties as they begin to move from the nomination battle toward the general election.
On the Democratic side, Senators Hillary Rodham Clinton and Barack Obama seem likely to continue their state-by-state struggle, after a night of tit-for-tat division of states and delegates, though Mrs. Clinton claimed the formidable prize of California.
But after months of disarray, Republicans seemed closer to coalescing around Senator John McCain of Arizona. As Mr. McCain logged victories in populous states, including California, and added more delegates to his count, he moved nearer his goal of wrapping up his competition with Mitt Romney of Massachusetts. A third Republican candidate, Mike Huckabee of Arkansas, underlined Mr. Romney’s weakness by posting a series of victories, in a performance that highlighted the discomfort social conservatives have with the field.
Mr. Huckabee’s relatively strong showing was both a blessing and a curse for Mr. McCain, though perhaps more of a blessing. It injected a small note of uncertainty into the Republican race, and potentially delayed the day when Mr. McCain would have the stage to himself. But Mr. Huckabee appeared to drain votes primarily away from Mr. Romney, contributing to his overall weak showing on this night.
This split in the road for Democrats and Republicans should — if and when Mr. McCain can claim his party’s nomination — be a welcome development for Mr. McCain, who would have time to begin quelling doubts about him among conservatives.
James C. Dobson, a longtime conservative leader, greeted Mr. McCain on primary day with a statement announcing that he would under no circumstances vote for Mr. McCain in November. In many states, the vote total for Mr. McCain’s main opponents — Mr. Romney and Mr. Huckabee, a Baptist minister — easily outweighed his own. Mr. Huckabee’s strong showing was all the more notable for the shoestring nature of his campaign, which has been limping along with little money and no victories since his win in the Iowa caucuses at the beginning of last month.
It is hard to see how Mr. McCain can be a strong general-election candidate — particularly going up against a Democratic Party so energized — without the support of the party’s conservative wing. Assuming Mr. Huckabee is unable to wound Mr. McCain as he wounded Mr. Romney, the results on Tuesday could give Mr. McCain time now to begin trying to repair breaches. The riveting competition between Mrs. Clinton and Mr. Obama could provide Mr. McCain some cover as he deals with this peacemaking.
The picture is decidedly less auspicious for the Democrats. These were the first head-to-head contests between Mrs. Clinton and Mr. Obama since John Edwards of North Carolina dropped out, and the results suggest that Democrats are fracturing along gender and racial lines as they choose between a black man and a white woman.
Surveys of voters leaving the polls suggested a reprise of the identity politics that has so long characterized — and at times bedeviled — Democratic politics. Black voters overwhelmingly supported Mr. Obama, suggesting an end to a period in which Mrs. Clinton could remain competitive with Mr. Obama for the support of that segment of the Democratic electorate.
Women went, by large margins, to Mrs. Clinton. But in one development that augurs well for Mr. Obama, white men — who had largely voted for Mr. Edwards before — appeared to be heading in his direction. And young voters also went overwhelmingly for Mr. Obama, suggesting a generational divide.
Tough nominating fights can be debilitating for parties. Mike Murphy, a Republican consultant, noted the financial advantage that Mr. Obama had going into the weeks ahead and said that Mrs. Clinton might well be tempted to fight back in a way that could leave the party polarized and provide an opening for Mr. McCain.
“This could put Hillary into a corner,” Mr. Murphy said, “and if she tries a real negative campaign, it could split the party and be a hangover in a general election.”
But the history of their contest — and the sensibilities displayed by Mr. Obama and Mrs. Clinton — suggests that would not necessarily be the case.
The most bitter period of their campaign was in South Carolina, when Mrs. Clinton and former President Bill Clinton repeatedly challenged Mr. Obama’s credentials and credibility. But after signs of backlash, she scaled back, and since then, the two have expressed their differences for the most part with fewer sharp edges. Should that tone continue, this contest may end without the bitterness Republicans were hoping for.
Finally, whatever the passions of Mr. Obama’s and Mrs. Clinton’s supporters — and by every measure, their passions are about as high as they ever get in politics — Democrats have throughout this year been unified by the intensity of their desire to win back the White House after eight years of President Bush.
And that, more than anything else, may continue to be the best thing Democrats have going as they enter this potentially turbulent period.