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

BLOOMBERG SAYS HE WON'T RUN BUT WILL BE ACTIVE
(Diane Cardwell, New York Times)
Bringing an end to a long flirtation with a bid for the White House, Mayor Michael R. Bloomberg has officially closed the door on a presidential candidacy this year. In an Op-Ed article published in Thursday’s New York Times, Mr. Bloomberg wrote that he still believed that a nonpartisan approach was needed to solve the country’s problems and that an independent candidate could win. But he will not run, he said.

THE OP-ED: I'm Not Running for President, But... (Michael Bloomberg, New York Times)

INSULTS, APOLOGIES FUEL OBAMA'S RISE
(Ben Smith, Politico)
In the course of the primary campaign, and perhaps in a preview of the fall election drama, Senator Barack Obama has accepted the apologies of three United States senators, a former senator, CNN and various lower-level supporters of Senator Hillary Clinton. Most of them have apologized for saying something insensitive about Obama’s race, his name, or his heritage. And the dynamic of outrage and offense this campaign has proved race to be a much touchier subject than gender. At times, Obama’s campaign has sought to downplay burgeoning outrage. At others, he’s stoked it for political advantage. But most of the flaps ended the same way: With Obama forgiving the alleged offender. Sometimes he’s accepted the apologies graciously, sometimes sternly, but always in line with his message. And that message of reconciliation – often explicitly racial reconciliation – is a central part of his campaign’s appeal. With a general election that appears likely to open him to more Republican attacks, and more line-crossing, the campaign ritual of offense and forgiveness appears likely to be repeated often this year. 

CLINTON CAMPAIGN POURS RESOURCES INTO TWO CRUCIAL PRIMARIES
(Anne E. Kornblut and Shailagh Murray, Washington Post)
Clinton advisers anticipate that she will come under immediate pressure from prominent supporters to consider leaving the race if she loses on Tuesday. That pressure probably would be conveyed privately at first, but quickly become public if she fails to heed the message. A split decision Tuesday would be likely to lead to similar pressure, her advisers said. Only by gaining ground against Obama in the delegate fight would she find the justification to keep going. Aides described Clinton as realistic about her precarious standing.

LONGTIME CLINTON AIDE RETURNS TO THE FRAY
(Adam Nagourney, New York Times)
Harold M. Ickes may be Senator Hillary Rodham Clinton’s last hope for winning the Democratic presidential nomination... “I’m a little dismayed by the lack of fight on the part of our staff,” Mr. Ickes, the assistant to the campaign manager, scolded an audience of Clinton staffers dispirited after Mrs. Clinton’s losses last week, before beginning a roll call of the presidential campaigns he had helped win and lose. Mr. Ickes, who has typically been a behind-the-scenes player, is stepping out front to make the public case for Mrs. Clinton, at a time when campaign advisers have pressed to lower the profile of her chief strategist, Mark J. Penn. But most of all, he is serving as the campaign’s general in the fight for superdelegates... In doing so, Mr. Ickes is drawing on his intimate knowledge of the Clintons and their political networks — as well as delegate selection rules he helped write at the Democratic National Committee.

CLASH ON IRAQ COULD BE MCCAIN-OBAMA PREVIEW
(Michael D. Shear and Shailagh Murray, Washington Post)
For McCain, the decision to pick a fight with Obama helps keep the presumptive GOP nominee from being overshadowed by the battle between Obama and Sen. Hillary Rodham Clinton (N.Y.) for the Democratic presidential nomination. It also gives him a chance to undermine confidence in Obama's foreign policy experience before the Democrat can turn full attention to the general election. But even as he focuses on a potentially decisive showdown with Clinton in four contests next Tuesday, Obama has made it clear he won't ignore the attacks from McCain. Generating headlines about an Obama-McCain showdown could also benefit Obama by creating the sense among Democratic primary voters that he is on the verge of becoming their party's nominee and also that he can hold his own against the Republicans.

SEARCHING FOR THE NEXT SOCCER MOM
(Karlyn Bowman and Ruy Teixeira, Wall Street Journal)
The evolution of American politics is bound up with demographic and geographic change. So what are the trends to watch in 2008? A number of them will be examined today at an American Enterprise Institute-Brookings Institution conference featuring leading demographers and geographers. Here are some: Hispanic voters are becoming increasingly important... Evangelicals are an important, but not overwhelming, force... The influence married voters have on elections is declining... The suburbs are the contested terrain... America's shifting class structure has reduced the white working class's political role... People are becoming increasingly likely to live close to those who look, act and think like them.

MCCAIN IN A GLASS HOUSE
(George Will, Washington Post)
Although his campaign is run by lobbyists; and although his dealings with lobbyists have generated what he, when judging the behavior of others, calls corrupt appearances; and although he has profited from his manipulation of the taxpayer-funding system that is celebrated by reformers -- still, he probably is innocent of insincerity. Such is his towering moral vanity, he seems sincerely to consider it theoretically impossible for him to commit the offenses of appearances that he incessantly ascribes to others. Such certitude is, however, not merely an unattractive trait. It is disturbing righteousness in someone grasping for presidential powers.

BLACK LEADER CHANGES ENDORSEMENT TO OBAMA
(Jeff Zeleny, New York Times)
That statement of support for Mr. Obama took the Clinton campaign by surprise and prompted several leading supporters to try to keep Mr. Lewis from defecting, fearful that other members of the Congressional Black Caucus would follow. Campaign advisers, as well as aides to Mr. Lewis, sought to dispute the Times report. In a statement on Wednesday, the congressman confirmed his switch to Mr. Obama. “I think the candidacy of Senator Obama represents the beginning of a new movement in American political history that began in the hearts and minds of the people of this nation,” he said. “And I want to be on the side of the people.”

RACE A WILD-CARD FACTOR
(Maria L. La Ganga and Mark Z. Barabak, Los Angeles Times)
When John McCain apologized to Barack Obama this week for the comments of his warm-up act at a rally, it was not the first time -- and probably won't be the last -- that the most competitive black presidential candidate in U.S. history has heard the words, "I'm sorry." In his yearlong quest to win the White House, the Democratic senator from Illinois has changed the rules of political engagement, forcing his rivals to step delicately in a normally no-holds-barred arena. As the possibility grows that voters may bestow the nation's highest public office on an African American, serial public apologies -- largely by Democrats -- show just how sensitive race remains. What is less clear is how race could help or hinder Obama, who has struggled to keep it in the background. 

MORE: Somali Dress is Just the Beginning (Peter Brown, Real Clear Politics)
It would be surprising if the whole question of what should and should not be out of bounds in the campaign does not become a more frequent feature in the general election fight against Republican John McCain.

EARLY OBAMA COMMITMENT ON MONEY BECOMES TARGET
(David D. Kirkpatrick and Jeff Zeleny, New York Times)
Mr. Obama proposed a novel challenge aimed at limiting the corrupting influence of money on the race: If he won the nomination, he would limit himself to spending only the $85 million available in public financing between the convention and Election Day as long as his Republican opponent did the same. Now his challenge to his rivals has boomeranged into a test of Mr. Obama’s own ability to balance principle and politics in a very different context. After taking in $100 million in donations, Mr. Obama is the one setting fund-raising records, presenting a powerful temptation to find a way out of his own proposal so that he might outspend his Republican opponent. And the all-but-certain Republican nominee, Senator John McCain, is short on cash and eager to take up the fund-raising truce.