A round-up of this morning's must-read stories.

OBAMA'S DELTA WIN
(Richard Wolffe, Newsweek)
Buoyed by an overwhelming edge among African-American voters, Barack Obama cruised to victory over Hillary Clinton in the Mississippi primary, posting a 54-44 percent margin and teeing up a crucial showdown in Pennsylvania, the next major contest in the quest for the Democratic presidential nomination. Obama, seeking to become America's first African-American president, has enjoyed strong support from black voters throughout the nominating process. But here in the Delta Tuesday night, the racial divide was especially stark. According to exit polls, Obama outpolled Clinton among black voters 91-9. White voters preferred Clinton by a slightly narrower 72-21 percent margin. If the outcome and the racial math was predictable, Mississippians did provide a few modest surprises at the ballot box.

RACIAL TENSIONS ROIL DEM RACE
(Ben Smith and David Paul Kuhn, Politico)
The Clinton and Obama campaigns are once again locked in tense fight over race, as both sides refuse to budge on the question of what constitutes an offensive comment, and what counts as a sincere apology. The argument over race and grievance could carry short term benefits for Hillary Clinton, and could boost her support among white voters in Pennsylvania who may be turned off by a more intense focus on Obama's race. Barack Obama's promise has been in part based on his dexterity in moving past the old-fashioned political battlegrounds - including the politics of race - where he's found himself battling Clinton in recent days. But a Clinton supporter's charge that Obama has received preferential treatment because he's black also carries serious dangers for her, as senior members of Congress and other superdelegates begin to signal discomfort with the Clinton campaign's increasingly sharp attacks. Notably, House Speaker Nancy Pelosi said Tuesday she thought Clinton's attacks on Obama had put a joint ticket out of the question.

DEMOCRATS IN A FIGHT TO DEFINE WINNER
(Patrick Healy, New York Times)
With the fight for the Democratic presidential nomination likely to go on for weeks or months, Senators Barack Obama and Hillary Rodham Clinton are battling to define what it means to be winning — and, in some instances, they are overstating their own advantage and understating the gains of the other... The Clinton campaign’s argument that Mrs. Clinton has been winning in Electoral College battlegrounds falls short somewhat because of Mr. Obama’s victory in a bellwether state, Missouri, and his success in states that Democratic officials believe they may have a chance to carry this fall. These include Virginia and Colorado, which have been increasingly electing Democrats to statewide offices, as well as traditional swing states like Iowa... As another counterargument, Mr. Obama has been toting up his victories to suggest a striking range of popularity in states that usually fall outside the Democratic electoral map. Yet though these states have helped give him a lead in pledged delegates, it appears far from likely that he would be able to carry some of them in a general election.

MCCAIN'S ROLE IN PLANE PACT HIGHLIGHTS TIES TO LOBBYISTS
(Michael D. Shear and Matthew Most, Washington Post)
To show that he's a crusader against wasteful spending and congressional corruption, Sen. John McCain repeatedly brags about his leading role in stopping a scandal-plagued air tanker contract between the Air Force and Boeing in 2004. Four years later, a $35 billion contract has been awarded to Europe's Airbus consortium to build the latest generation of tanker planes. The decision has sparked anger from Boeing's congressional supporters and critics of outsourcing. It has also focused attention on McCain's reliance on lobbyists in his campaign for president because his finance chairman and several other top advisers lobbied for Airbus last year when it was in fierce competition with Boeing for the Air Force contract. 

MUTUAL CONTEMPT
(Michael Crowley, The New Republic)
It's little wonder that Obama and McCain would be casting each other as fakers. At the core of each man's political identity is the image of a reformer determined to take on and reshape the corrupt culture of Washington, D.C. To Obama, McCain is a fixture of that system, one whose reform talk belies his debts to the GOP establishment and its lobbyist machine. McCain, meanwhile, sees Obama as an upstart self-promoter whose talk about reform isn't matched by a record of hard work to achieve it. "In a weird sort of way, they're fighting over a change-and-reform mantle from two ends of the same argument," says Dan Schnur, a former senior aide to McCain. And that was never more obvious than in a 2006 clash between the men, well before Obama was even a candidate. That episode revealed the importance of reform to both men, but also the pitfalls they're finding as they walk the high ground. 

DEMOCRATS IN FLORIDA ARE NEAR PLAN FOR NEW VOTE
(Abby Goodnough, New York Times)
Democratic Party officials here are close to completing a draft plan for a new mail-in primary that would take place by early June, a proposal that seeks to give Florida delegates a role in the party’s presidential contest, several people involved in the discussions said Tuesday. A spokesman for Senator Bill Nelson, a Democrat who has been pushing for a mail-in contest, said Mr. Nelson expected the Florida Democratic Party to finalize details of the complex plan as soon as Wednesday. The state party would most likely submit the proposal to Howard Dean, chairman of the Democratic National Committee, by week’s end.

THE DEMOCRATS, WRESTLING TO NEGOTIATE AN ENDGAME
(Kevin Merida, Washington Post)
The Democrats are stuck in their own mud. They have no scripted ending to this titanic battle, no scenario ready for wide embrace. Or any embrace. Or even a handshake. On one level, the historic competition between Obama and Clinton has energized the party, boosted primary turnouts, spawned legions of new voters and campaign volunteers. But on the let's-get-real level, Democrats have problems even a blind man can see. Their primaries and caucuses have revealed labor splits, racial and ethnic splits, gender splits, age and class splits, and a rivalry that is getting nastier by the day. 

CLINTON'S PENNSYLVANIA PLAN
(Amy Chozick, Wall Street Journal)
In the six weeks leading up to the Pennsylvania primary, the Clinton campaign will blanket the commonwealth with events, recruit thousands of volunteers and throw strategic attacks at rival Sen. Barack Obama... Campaign staffers say that in Pennsylvania Sen. Clinton will rely more heavily on volunteers and a more frugal, homegrown effort. "I wasn't around for Iowa, but I think people in Pennsylvania want a more personal approach," says state campaign spokesman Mark Nevins, who joined the staff two weeks ago. Sen. Clinton is expected to host more interactive roundtable events to talk to voters about the economy -- an approach that paid off in Ohio, where people have similar economic concerns.

MORE: Pennsylvania Isn't a Lock for HRC (David Paul Kuhn, Politico)
With the support of the state’s political establishment and favorable demographic terrain, Pennsylvania's April 22 primary is widely viewed as Hillary Clinton’s to lose.  But it’s hardly a lock, especially if Barack Obama can make inroads with a few key constituencies outside of his reliable base of affluent whites, liberals, African-Americans and the youth vote.

TWO NIGHTS
(Chris Jones, Esquire)
So on the day before the primary, the tension in the back of the bus weighed heavy. This was it, and everybody knew it, and McCain was feeling nostalgic as well as nervous. He talked about the past, and he asked his staff to mirror, as closely as possible, the final day of his campaign eight years earlier. He held his one-hundredth town hall in Peterborough, where he had first dished out ice cream. He made stops in the same cities -- Keene, Hanover, Concord -- he had stopped in last time around, ending each of his speeches by saying, "I will never let you down," perhaps one last jab at the people who had left him for dead months earlier. Now he listened to the crowds cheering, and he remembered. He wanted so badly to remember that he made the bus stop in Portsmouth in the dark -- Portsmouth, where he had held his final event in 2000 and now did again. He slept in the same hotel room, the Presidential Suite on the eighth floor of the Crowne Plaza in Nashua. The next day, he pulled on the same green sweater he had worn back then; he jingled the pennies in his pocket that he had picked up over the course of the previous week, but only if he spied them heads up; he checked the weather and was heartened that there would be drizzle in the northern part of the state, because rain had been good luck for him on Election Day.