While I favor Sen. Barack Obama for the Democratic presidential nomination, I fail to find sympathy for daily calls by political and media figures for Sen. Hillary Clinton's immediate withdrawal from the contest. Typical is David Brooks' argument that Hillary's chances are now very remote but that she will keep campaigning, Battle of Verdun style, because she can't help herself. Obama leads Clinton in convention delegates and the popular vote. Upcoming primaries and caucuses — with the notable exception of the April 22 Pennsylvania primary — seem likely to end in his favor. If Michigan and Florida do not conduct June redos of their unsactioned January primaries, Clinton will lose her last big opportunities to close Obama's delegate lead. So-called "super delegates," who will comprise 20 percent of the total at Democrats' August convention in Denver, have been steadily moving into Obama's column. (Super delegates are elected officials and party leaders not elected in state primaries or caucuses). Speaking of those super delegates, another argument against Clinton's continuing in the race is advanced by conservative law professor John Yoo, who sheds tears at the prospect of super delegates extracting promises from either candidate, thus tying the eventual nominee's hands in the White House. Surely the Founding Fathers would disapprove, scolds Yoo. All the factors, excluding Pennsylvania, currently favor Obama. But a full month remains until the Pennsylvania primary, which Clinton almost surely will carry. And five months remain until the Democratic national convention. What if, in those five months, any of the following transpire: Sen. John McCain, the Republican presidential nominee, continues to run more strongly in opinion polls against Obama than against Clinton. McCain's lead over Obama becomes substantial. The inflammatory statements of Obama's former pastor continue to remain at the center of political attention. Obama's Philadelphia speech earlier this month masterfully handled the issue within the Democratic Party. But there is evidence that the matter is peeling away former independent and Republican support from Obama — and could jeopardize as well support among white Reagan Democrats in northern industrial states the Democratic ticket must carry in November. (Analysts will examine carefully the ethnic, racial, gender, and religious breakdowns in the Pennsylvania primary voting. Pennsylvania is exactly the kind of state where Obamerosion could take place). One key question: Will film or tape surface showing Obama in attendance at services where his pastor made particularly outrageous statements? Or, a fresh political, personal, or ethical scandal might envelop Obama. Then what? The ongoing trial of his Chicago fixer/patron will keep popping up in the news. Will new disclosures embarrass and hurt Obama? Hillary Clinton, you can be sure, will try to remain on the offensive during the entire period until the Denver convention, trying to force Obama into a mistake, throwing him off his basic campaign message, and making his nomination and election appear less inevitable. As a scarred veteran of many previous Democratic conventions and nominating battles, I can attest to the destructive effect that a divisive nominating contest can have on the party's fall election chances. A garden-variety, dull convention normally gives the party nominee anywhere from a 10- to 20-point bounce in national opinion polls. (Massachusetts Gov. Mike Dukakis, for example, gained 18 percentage points against George H.W. Bush after Democrats' 1988 Atlanta convention). But Democrats' divisive 1968 and 1972 conventions sent nominees Hubert Humphrey and George McGovern into the fall campaigns with comparable dips in popularity. In historical terms, the 2008 combat between Obama and Clinton has been downright mild. With little difference between the two on major international and domestic issues, dialogue has begun to center on such matters as Obama's pastor and whether or not Hillary actually ducked gunfire during a 1996 visit to Bosnia. New Mexico Gov. Bill Richardson and Sen. Chris Dodd (poor babies) recently have related that Hillary subjected them to telephone abuse when they told her of their endorsements of Obama. Clinton adviser James Carville last weekend crudely termed Richardson "a Judas" for his Obama endorsement. Both campaigns' daily media briefings have become nasty about the opposition. But none of this begins to approach the toxic stuff purveyed at the 1948 Democratic convention, when Dixiecrats and Henry Wallace supporters both took a walk; the 1960 convention, when Lyndon Johnson and Adlai Stevenson supporters both tried to stop John F. Kennedy's nomination; the dreadful 1968 and 1972 bloodbaths; or even the spirited 1984 competition between Walter Mondale and Gary Hart. It most approximates the plain-vanilla 1992 competition among Bill Clinton, Paul Tsongas, and Jerry Brown or the 2000 contest between Al Gore and Bill Bradley. (Democrats carried the 1948 and 1960 elections, by the way, despite divisiveness at their national conventions). Another fact should not be forgotten: In their haste to keep unseemly conflict off national television, both major parties in recent years have reduced their national conventions into brief, made-for-TV specials in which a few hours of prime time are devoted to the nominations of the presidential and vice-presidential candidates and their acceptance speeches. Former gavel-to-gavel coverage of platform, rules, and credentials fights — and multi-ballot nominating contests — has long since disappeared and, as a result, have caused viewers to channel surf. There is no reason whatever that Hillary Clinton, with so many weeks remaining until the Denver convention, should throw in the towel now. One would hope that both her campaign and Obama's will temper their language and focus debate on substantive rather than personal issues. But some of the latter will be inevitable. Hillary has every right to remain on stage as long as she wishes.