U.S. SEN. Hillary Clinton, who famously knocked back a shot of Crown Royal while wooing Indiana voters several weeks ago, may need a few more stiff belts after last night's primaries.

A blowout win for her Democratic rival, Sen. Barack Obama, in North Carolina — coupled with a too-close-to-call race in Indiana — widened Obama's lead in delegates and made her quest for the presidential nomination seem more daunting than ever, if not impossible.

"It's now a question of the irresistibility of mathematics," said G. Terry Madonna, the political scientist and pollster from Franklin & Marshall College. He said Obama's strong showing may now sway many of the more than 200 undecided party chieftains, the unelected superdelegates, to move toward the Illinois senator.

If Indiana and North Carolina proved anything yesterday, it was that Democrats there were no different from elsewhere — Obama won big among blacks and college grads; Clinton carried white, working-class voters.

The problem for Clinton is that she needed something radically different from the status quo to have a shot at undoing Obama's lead in delegates who will attend the party convention in Denver this August — and in popular votes in primaries from coast to coast.

The Associated Press estimated that Obama picked up 57 delegates yesterday to 48 for Clinton, increasing his overall lead to 1,802-1,656 with 2,025 needed to win the nomination. The winner will face Republican Sen. John McCain in November.

In North Carolina — as in every other Southern state except for Clinton's former home in Arkansas — a large African-American Democratic electorate combined with high-tech workers and a large college population to give Obama a substantial win. He had 56 percent of the vote last night, compared with 42 percent for Clinton, with 89 percent of votes counted.

In Indiana, where Clinton made a populist pitch in a Rust Belt state with major job losses and where the black vote is closer to the national average, the New York senator held together her coalition of older and blue-collar voters — but just barely. She led 51-49 percent with 91 percent of votes counted, but ballots from the Obama stronghold of Gary, Ind., were still out.

For Clinton, who started the seemingly endless primary season many months ago with a aura of inevitability, the tight Hoosier State primary may have been a case of too little, and too late.

"The math is inescapable at this point," Missouri Sen. Claire McCaskill, a key Obama ally, told MSNBC last night. Obama aides were predicting to reporters that their candidate would have a majority of the pledged delegates by the Oregon and Kentucky primaries May 20.

Obama, looking more ebullient than any time in weeks, told an enthusiastic victory rally in Raleigh, N.C., last night that he was within 200 delegates of securing the nomination and said last night proved not the "game changer" that some pundits and the Clinton campaign had predicted.

"Today, what North Carolina decided is that the only game that needs changing is the one in Washington, D.C.," Obama declared.

He also seemed to address suggestion by some journalists and voters that he lacks the proper kind of patriotism, speaking of the America that gave opportunities to him and his working-class relatives.

"That's the America I love that the America you love, and that's the America that we are fighting for," he said.

Clinton, appearing before her faithful in Indianapolis, put the best possible face on the results, calling Indiana the "tie-breaker" after her recent win in Pennsylvania and Obama's victory in the Tarheel State.

"Tonight, we've come from behind — we've broken the tie, and thanks to you it's full speed onto the White House!" she said.

Despite evidence that the recent uproar over Obama's ex-pastor, the Rev. Jeremiah Wright, didn't have a huge impact yesterday — most voters told exit pollsters they made up their minds a month ago or longer — the Clinton campaign seemed to still hold out hope for that late "game changer."

Without any evidence to support it, top Clinton adviser Harold Ickes tried to warn last night in an interview that an unvetted Obama might face an unspecified "October surprise" that could cost Democrats the election.

Instead, the voting patterns that have dominated the Democratic primary balloting — ever since John Edwards dropped out and made it a two-person race right before February's Super Tuesday — held again last night.

If anything, according to exit polls, Obama has solidified his support among African-American voters energized by the prospect of the nation's first black president — winning as much as 90 percent of that key voting bloc.

He also continued to win overwhelmingly among voters under age 40 and among those with college degrees. In fact, the MSNBC exit poll of North Carolina showed Obama with a whopping 45 percent edge among the roughly one-in-eight voters who were age 29 and younger. Clinton, meanwhile, won handily among senior citizens.

"I've called it the hardening of the demographic arteries," said Madonna, noting that both candidates continue to win states where their core supporters live, with little to change minds made up early in the race. The MSNBC survey also said that close to half the voters in North Carolina said "change" was the most important issue, and those voters were overwhelmingly for Obama.

Clinton had the edge among Democrats seeking "experience" or more focused on specific issues such the economy, health care and Iraq, but that wasn't enough for a win.

In Indiana, Obama's surprisingly strong showing is leading some opponents to question the wisdom of her strategy there, which centered on a push for a summer "holiday" on the 18-cents-a-gallon federal gas tax.

Some experts wondered whether her idea actually helped Obama — who accused Clinton of pandering for votes — by making him look more presidential. *