“One of Bush’s liabilities coming in was that he was seen as a silver spooner who had lived a charmed political life,” said Dan Bartlett, a top aide to Mr. Bush in Texas and in the White House. Overcoming Mr. McCain, Mr. Bartlett said, was a show of toughness. “He took a punch and got up off the mat,” Mr. Bartlett said of Mr. Bush. “You could argue the same about Obama now.”

3. SHE LED HIM TO THE WORKING CLASS

If Mr. Obama goes on to win the nomination, one of the signature challenges of his general election campaign will be his ability to win over the traditional Democratic blue-collar voters that have flocked to Mrs. Clinton in states like Ohio and Pennsylvania. In a sense, Mrs. Clinton’s success with this constituency exposed his vulnerability with it — a vulnerability he might not have known existed to such an extent had Mrs. Clinton dropped out early and Mr. Obama breezed to the nomination.

Image WORTHY RIVAL Hillary Rodham Clinton has tested, and maybe toughened, her opponent. Credit... Damon Winter/The New York Times

In recent weeks, Mr. Obama started doing more retail events, talked more about his family’s economic challenges growing up (to address a creeping rap of elitism, however ill-fitting that label is). He saw what played well (a tough-love opposition to the gas tax holiday) and what needed work (his bowling). He worked to escape the pigeonhole that he was a big arena rock star. He has recently done fewer big rallies and more one-of-you performances (pick-up hoops games in Indiana). He seemed to heed Mrs. Clinton’s recurring criticism that Mr. Obama was all about “creating an atmosphere” and “giving great speeches.” There have been fewer shots of a larger-than-life Mr. Obama at a podium, more of him face-to-face with workers (or waffles). More listening photo ops, in other words, and fewer talking ones.

4. THE WRIGHT FIGHT

While this doesn’t involve Mrs. Clinton directly, the long primary battle allowed the emergence, and re-emergence, of Mr. Obama’s former pastor, the Rev. Jeremiah Wright Jr., to take place now, rather than later. It’s generally assumed that Mr. Wright would have been an issue at some point, so better for Mr. Obama now than October.

“It’s entirely likely that we’ll hear from Reverend Wright again,” said Dan Payne, a Democratic media consultant. “But from now on, the Obama people will be able to play it as old news.”

As a corollary to the “made him angry” benefit, Mr. Obama’s handling of the Wright controversy signaled an evolution that could serve him well. “The Reverend Wright thing struck me as Barack learning to be president,” said Richard Ben Cramer, author of “What It Takes,” the exhaustive examination of six candidates for president in 1988. “When your friend causes you trouble, a president gets rid of those friends. It may come to pass that they become friends again. But for the time being, this is more important.”