It has become a campaign like no other. Continuing to throw conventional wisdom out the window, it defies description or logic. Every time you think you have a handle on it, something comes along to put you back at square one.

The most mind-numbing thing of all: People are still citing poll numbers as to what will happen in November, for gosh sakes. We can't even predict what's going to happen tomorrow, let alone six months from now. Heck, we couldn't even predict the New Hampshire primary on the day of the New Hampshire primary.

Where to begin? Here are some questions that might not be answered anytime soon.

Is it mathematically impossible for Clinton to win the nomination? The numbers don't look promising. When you look at the way the Democrats apportion their delegates in the primaries (unlike the Republicans' "winner-take-all" system in many states), it is very hard to see how, when all is said and done on June 3, she will find herself in the delegate count lead.

Clinton won a sizable, nine-plus point victory in Pennsylvania's primary, but impressive as it was, she netted only 10 delegates out of it. As of this writing, Obama has 1,730 delegates, compared with 1,597 for Clinton - 2,025 are needed for the nomination.

Where is she going to get the delegates she needs to not only take the lead, but also win at the party convention in Denver? Obviously, one answer would be the 290 or so superdelegates who haven't yet publicly committed to a candidate. But even in the wake of his Pennsylvania defeat, Obama has continued to pick up more supers than Clinton. Since that primary, Obama gained nine, compared with five for her.

Clinton picked up North Carolina Gov. Mike Easley, Reps. Ike Skelton of Missouri and John Tanner of Tennessee, Pennsylvania state AFL-CIO President Bill George and New Hampshire party bigwig Kathy Sullivan. Obama, on the other hand, got Oklahoma Gov. Brad Henry; Sen. Jeff Bingaman of New Mexico; Reps. Baron Hill of Indiana, Bruce Braley of Iowa, Ben Chandler of Kentucky and David Wu of Oregon; and party notables Richard Machacek (Iowa), Audra Ostergard (Nebraska) and Charlene Fernandez (Arizona).

What's coming up? All eyes are on May 6 and the primaries in Indiana and North Carolina. They are the most important contests in the history of the republic simply because they are next. It's been that kind of a campaign. The sense is that Obama wins in the Tar Heel State, but it's even money in Indiana. Clinton is favored in West Virginia on May 13 and Kentucky a week later. But let's get past May 6 first.

When does it end? Sometimes, you need to decide for yourself when it's time to pull up stakes and fold your cards. There were two vastly different approaches in 1980. George H.W. Bush, in his bid for the Republican nomination that year, went into the May 20 primary badly trailing front-runner Ronald Reagan. Bush's victory in Michigan was substantial - 57 percent to 32 percent. But Michigan still wasn't enough. Less than a week later, he figured there was no way he could surpass Reagan in the delegate count and ended his campaign.

On the Democratic side that year, it wasn't as tidy. Sen. Edward Kennedy (D-MA) took his fight to President Carter behind the last round of primaries in early June - when Carter won a majority of the delegates needed to assure him renomination - all the way to the convention, where the Kennedy forces fought the Carter forces over the rules and platform, all unsuccessfully.

It has been said that when a battle for the nomination goes all the way to the convention - as with Kennedy vs. Carter in 1980, and Republicans Reagan vs. Ford in '76 - the party's task of uniting in time for November is that much more difficult. This may be true, though the defeats of Presidents Ford and then Carter are more complicated than that.

Still, Democrats are increasingly concerned that the bad blood between Clinton and Obama may spill out onto the general election. A sizable number - perhaps as much as one-third - of Clinton voters in Pennsylvania have indicated they wouldn't vote for Obama in the fall; the number of Obama voters who would bypass a Clinton vote was smaller, though still significant. I suspect there is no way to know in the heat of a battle that has become so personal what kind of party fallout we'll see in November. Factors such as the war, rising gasoline prices, the unpopularity of President Bush and the general unease of the economy all point to a Democratic year. But if there are sizable defections to Republican John McCain, then the Dems' cakewalk will instead become a pie in the face.

What to make of Bill Clinton's role? Probably the most popular Democratic president since JFK, he has lost much of the goodwill he had among African Americans, long his most steadfast of supporters. This began with his comments in the racially polarizing conversations surrounding the South Carolina primary and continues to the present - just the other day, Clinton attacked Obama and the media for playing the racial card against him.

For much of the campaign, it has been about Bill Clinton, and while no one can connect with voters like he can, nobody seems to be squandering a legacy as fast as he has. Rep. Jim Clyburn (D-SC), the leading black member of the House who has not endorsed a candidate, has said African Americans are "incensed" over Bill Clinton's statements, and Clyburn indicated that attacks on Obama by the Clintons could make it impossible for Obama to win the general election.

Who has the most votes? If you're Hillary Clinton, you do, because you count what happened in Michigan and Florida, two states she won. But no delegates were awarded because the states moved up their primaries to a date deemed unacceptable to the Democratic National Committee. It's a bit disingenuous to include vote totals from the two, and no one outside the Clinton camp counts them. This "new math" is no doubt a strategy to help her make a case to the superdelegates.

Of course, it's delegate totals, not popular votes, that will determine the nomination, just as it's electoral votes, not popular votes - as Al Gore learned - that get you to the White House. Besides, Hubert Humphrey had more popular votes than George McGovern in their battle for the 1972 Democratic presidential nomination. Was McGovern not the rightful nominee?

Can Obama win the white vote? Pennsylvania exit polls showed that white voters, especially blue-collar Dems, went overwhelmingly for Clinton. Everything from his skin color to his "bitter" comment in San Francisco to charges of elitism to his association with the Rev. Jeremiah Wright has been blamed for that. All may be true. And it may portend big trouble for Obama in November. But for the record, no Democratic presidential candidate has won a majority of white voters since Lyndon Johnson in 1964.

Is the Rev. Jeremiah Wright the gift that keeps on giving? Some Republicans think so. Whereas we once talked about Obama as having "transcended" race, race seems to be all we're talking about now. And much of the blame lies with Obama's former pastor, who pulled off a trifecta in the past few days with his Bill Moyers interview, an NAACP speech and his appearance at the National Press Club in Washington.

If nothing else, Wright's visibility this week is a stark reminder to the Obama campaign that this guy is not going away. When Obama gave his widely praised speech on race in Philadelphia in March, it was to explain his complicated relationship with the fiery preacher, who among other things blamed the U.S. government for spreading the AIDS virus in the black community and said America "reaped what it sowed" on Sept. 11. But Wright's antics at the press club forced Obama to take action once again. Obama's remarks to reporters in North Carolina on Tuesday were evidence that the speech in Philly was little more than a Band-Aid.

Has Obama rescued his candidacy? Hard to tell. More and more Democrats are now wondering if Wright will be Obama's albatross for the fall. Obama, himself, is no doubt wondering why Wright decided to put on his show now, at the critical juncture of the presidential race. For all the attention Bill Clinton craves for himself, there is no question he wants his wife to become president. The same, as we've learned this week, cannot be said about Wright and Obama.

Finally, did I really say on CNN that Hillary Clinton reminded me of Glenn Close in Fatal Attraction? I did. I wish I hadn't. It was a facile and dumb comparison. And for all the people who took their marching orders from the Clinton campaign's e-mail blast instructing them to express their displeasure to me, rest assured, I have read every note. Some have been quite thoughtful, enough to establish some sort of dialogue. Others, regrettably, have contained an astonishing amount of vitriol and hate. It's distressing that many of those who complain the most about bigotry and ignorance exhibit it themselves.

The point that I was inartfully trying to make, as I wrote in one e-mail, is that I was mocking the "when-will-Hillary-drop-out?" conversations that have been going on since New Hampshire - as in, well, if she loses N.H., she's finished. If she loses Ohio or Texas, she's gone. I wanted to make the point that she's not leaving the race any time soon, nor should she. She wins in Pennsylvania by nearly 10 points and people still want to know when she's getting out? Nonsense. I concede that I damaged my case by making the Glenn Close comparison, but I was trying to say sorry, you're not going to get rid of her. This is only the seventh inning. The race hasn't been going on "too long." In fact, these states - Indiana, North Carolina, Oregon, etc. - haven't been part of the conversation for decades. Let the people have their say and then we'll see who should drop out.

By Ken Rudin, NPR, April 30, 2008