BREAKING NEWS
NBC News and news services
VIDEO: The move pushes Democrats closer to total control of the U.S. Senate

WASHINGTON - Veteran Republican Sen. Arlen Specter disclosed plans Tuesday to switch parties a move that will push Democrats closer to total control of the U.S. Senate.
Specters switch is a huge boost for President Barack Obama as he tries to advance his agenda on energy policy health care reform and other issues.
With 60 votes in the 100-seat chamber Obamas fellow Democrats could stop Republican filibusters stalling tactics used to delay or defeat legislation.
Specter would give Democrats at least 59 Senate seats. There is one vacancy from state of Minnesota where Democrat Al Franken holds a narrow lead in a race still being disputed in courts.
Under Senate rules a single senator can object to consideration of a bill in which case it takes a 60-vote super-majority to bring a bill to the floor or end debate so a final vote can be taken.
However there is no guarantee that the Pennsylvania senator will vote with the Democrats on every issue. With the presence of moderate Democrats and contested regional issues the risk of a fractured caucus is a congressional reality.
In our caucus we dont have any automatic votes for anything said Senate Judiciary Committee Chairman Patrick Leahy. I expect him to be as just as independent as ever.
Anyone who says the presidents agenda can slide right through here is wrong added New York Sen. Charles Schumer. But the really good news for us is that the Republican sort of knee-jerk filibuster at every whim cannot happen.
Political philosophy at odds
In a statement Specter said I now find my political philosophy more in line with Democrats than Republicans...It has become clear to me that the stimulus vote caused a schism which makes our differences irreconcilable. Several Senate officials said a formal announcement could come later in the day or Wednesday. Specter planned a news conference for Tuesday afternoon.
Specter 79 and a veteran of 29 years in the Senate is one of a handful of Republican moderates remaining in Congress in a party now dominated by conservatives. Several officials said the White House as well as leaders in both parties had been involved in discussions leading to his move.
Specter faced an extraordinarily difficult re-election challenge in his home state of Pennsylvania in 2010 having first to confront a challenge from his right in the Republican primary before pivoting to a general election campaign against a Democrat.
I am unwilling to have my twenty-nine year Senate record judged by the Pennsylvania Republican primary electorate he said in the statement.
I dont have to say anything to them. Theyve said it to me Specter said when asked in a Capitol corridor about abandoning the Republicans.
Lets be honest...
Republican National Committee Chairman Michael Steele responded to the switch in a statement saying Lets be honest Sen. Specter didnt leave the GOP based on principles of any kind. He left to further his personal political interests because he knew that he was going to lose a Republican primary due to his left-wing voting record.
There were kinder words from Senate Majority Leader Harry Reid: I welcome Sen. Specter and his moderate voice to our diverse caucus and to continuing our open and honest debate about the best way to make life better for the American people.
Sen. Arlen Specter is one smart senator added Sen. Robert Byrd D-W.Va. He is an independent thinker of the type that the framers of the Constitution had in mind when they conceived the office of U.S. senator.
100 days
Specters move came a day before Obama marked 100 days in office.
A senior White House official speaking on the condition of anonymity because no announcement has yet been made said Obama was handed a note while in the Oval Office during his daily economic briefing.
The note said: Specter is announcing he is changing parties. A few minutes later Obama reached Specter by phone and told him you have my full support and that the Democratic Party is thrilled to have you.
Specter had publicly acknowledged that to win in 2010 he would need thousands of Pennsylvania voters who switched from Republican to Democrat last year to vote for Obama to flip back to the Republicans to cast ballots for him.
Powerful panel positions
As one of the most senior Republicans in the Senate Specter held powerful positions on the Judiciary and Approporiations panels. It was not clear how Democrats would calculate his seniority in assigning committee perches.
Specter has long been an independent Republican and he proved it most recently when he became one of only three members of the Republican party in Congress to vote for Obamas economic stimulus legislation.
As recently as late winter he was asked by a reporter why he had not taken Democrats up on past offers to switch parties.
Because I am a Republican he said at the time.
NBCs Ken Strickland contributed to this report.