By John Zogby
Pollster and independent political analyst
Has Barack Obama won the Democratic presidential nomination?
It is certainly tempting to make this conclusion based on his amazing string of victories on Saturday and Tuesday evening.
Mr Obama is popular with moderate and independent voters
But the short answer to the question has to be no.
Senator Obama has now more states than his rival, Senator Hillary Clinton, including the last six (plus the Virgin Islands and the national capital, Washington DC) and he now leads among delegates pledged to vote for him at the Democratic National Convention.
In addition to his momentum of victories, he has made significant inroads into constituencies that were the core of his opponent's support.
Thus, in Virginia and Maryland, exit polls revealed that he tied with Senator Clinton among white voters, and actually defeated her among women, lower-income voters, rural voters, those over 65 years of age, Catholics, and Hispanics.
Those numbers are very important because they show the meaning of momentum, which is so vital to understanding the primary process, and because they take away one of the main arguments that has been used against Mr Obama: that he is the African-American candidate who has more limited appeal than Mrs Clinton with mainstream voters.
Mr Obama's victories are becoming numerous and sizeable.
In addition to expanding his political base among African Americans and young voters, he also has consistently demonstrated a greater appeal than Mrs Clinton among independents and moderates, swing groups that will give shape to the general election in November.
There is also an almost cult-like quality to Obama's following
This in itself is a powerful argument for Obama's nomination, because the Democratic nominee will likely face Republican Senator John McCain, who is very popular among centrist voters.
Above all, Obama generates an intense and growing level of emotion among young voters.
They are voting in record numbers in the primaries and can make the difference between victory and defeat for him in November.
On the other side, Senator Clinton's campaign has been going through a rough patch.
She is having difficulty raising money, she has accepted the resignations of both her campaign manager (a Hispanic woman and long-time aide whose departure has not gone down well among Hispanics) and deputy campaign manager.
Her staff are already pointing fingers of blame at each other - never a good sign when so much positive energy is needed.
Perhaps more than anything else, there is a growing feeling of "Clinton Fatigue" among insiders and ordinary voters.
Mrs Clinton still has core support among older women and Hispanics
After all, a voter in November 2008 has to be at least 42 years old to have voted in a general election in which a Bush or a Clinton did not emerge as the victor.
And finally, there are almost 800 "super-delegates" - elected officials or Democratic party leaders - who also get a vote at the convention.
A key question: why aren't these establishment types already backing Senator Clinton?
Why are they waiting until the last minute?
To me, that speaks volumes.
On the other hand, this deal is not closed.
At this time of writing, the two candidates are nearly tied among pledged delegates, and even if Obama wins all of the remaining states with 55% of the vote, he still falls short of the 2,025 total delegates he needs to secure the nomination.
Meanwhile, Clinton would continue to rack up almost the same number of delegates based on proportional voting.
Clinton is formidable.
She is after all a Clinton - she and her husband are popular, dogged, able campaigners.
She has been a successful senator and has core support among older women and Hispanics, both of whom can propel her to victory in Texas and Ohio and get her campaign rolling again.
There is also an almost cult-like quality to Obama's following.
He generates a lot of heat and excitement - but can he sustain it?
Will the press continue to love him tomorrow?
And if negative (or at least not glowing) stories begin to appear in rapid succession, will his supporters still be so enthusiastic?
So the nomination battle is far from over.
But - at least for now - Obama has truly taken his campaign much further than his opponents ever believed possible.
John Zogby is the President and CEO of Zogby International, an independent polling company in the US.