Quotes of the Day

Hillary Clinton's popular vote victories in Texas and Ohio fundamentally change the race for the Democratic presidential nomination in at least one important way: She's still in the race for the nomination. Clinton's long, arduous campaign might have ended abruptly if Obama delivered a knockout blow in either state.

Instead, Clinton will fight on for at least the next seven weeks, until Pennsylvania votes on April 22. To get an idea of how long a period that is in political years, the Iowa caucuses — remember them? — were only eight weeks ago.

Clinton is emboldened not just by her Tuesday wins, but by several other developments over the past few days. She has now taken the popular votes in all the major industrial states that have held contests, except for Obama's home state of Illinois. Additionally, from Clinton's point of view, Obama is only now beginning to experience the aggressive media scrutiny standard for a serious presidential candidate. And she has finally found an advertising and rhetorical strategy to highlight Obama's relative lack of national security experience — his greatest weakness with voters.

But the March 4 results have not changed Obama's strongest talking point (and reality point) for why Clinton should exit the Democratic race: Math. It appears numerically impossible for her to overtake his lead among elected delegates.

Neither Obama nor Clinton can win the 2,025 delegates required for nomination without some combination of elected delegates (those chosen in primaries and caucuses) and superdelegates (party and elected officials who are automatic delegates to the Democrats' Denver convention this summer). About 800 of the approximately 4,000 delegates are superdelegates and several hundred of them are still uncommitted to either candidate.

Given the remaining contests — many with electorates favorable to Obama — Obama's existing hundred-plus delegate lead, and the rules by which Democrats apportion delegates, it is almost a political and mathematical certainty that Obama will have an elected delegate lead at the end of the process, barring dramatic, unforeseen circumstances.

Some of the upcoming states to vote — including Wyoming on Saturday and Mississippi on March 11 — are likely to swing strongly for Obama, and certainly show no signs of being Clinton blowouts. The same goes for North Carolina on May 6 and Oregon on May 20.

Other contests might be more favorable for Clinton (Pennsylvania, Indiana, Guam, West Virginia, Montana, and South Dakota), but even decisive wins in those states — say, in the 60-40 range — would still leave her behind in both elected delegates and the overall count. That remains true even if Clinton somehow succeeds in getting the disputed delegates from Florida and Michigan seated at the convention.

Clinton's only hope of winning a majority of the delegates is to overtake Obama's elected delegate lead by winning the bulk of the remaining superdelegates.

This is the heart of Clinton's multi-dimensional challenge. Obama has of late signed up more superdelegates than Clinton in part because they are swayed by his lead in elected delegates. Yet unless there is a significant change in the overall dynamic — a major Obama blunder or scandal, for example — he is likely to continue accruing superdelegates regardless of Clinton's big March 4 wins. Also, the act of securing the nomination with unelected convention votes could be considered by many Obama supporters as highly undemocratic, embittering and dividing the party on the eve of the general election.

So Clinton lives to run for another seven weeks. But if you believe in the power of numbers, the candidate of inevitability is Barack Obama.

• Mark Halperin
• With key wins in big states, she has cause for optimism — but Mark Halperin says optimism can't beat delegate math