March 28 (Bloomberg) -- Pennsylvania Senator Bob Casey endorsed Democratic presidential candidate Barack Obama today, providing the Illinois senator with a boost in a state where rival Hillary Clinton has the lead.

``This campaign is a chance for America to chart a new course, to go down a different path,'' Casey, a Democrat, said today at an Obama rally in Pittsburgh. Obama offers a ``new type of politics and a path of hope and healing.''

The endorsement gives Obama an important ally in his effort to win over voters in Pennsylvania's April 22 primary, the next contest in the Democratic nomination race and a crucial one for Clinton. Casey got 59 percent of the vote when he won election in 2006 and he may help Obama make inroads with blue-collar workers, a mainstay of Clinton's support.

Clinton has the support of other high-level state officials, including Governor Ed Rendell, Representative John Murtha and Philadelphia Mayor Michael Nutter.

Casey, a so-called superdelegate who has a vote at the Democratic convention in August, previously said he would stay neutral before the primary. Obama said he didn't press Casey, the son of a former Pennsylvania governor, for the endorsement.

``I understood we are behind in Pennsylvania. It would have been easy for Bob just to stay out, to stay neutral,'' Obama said today. ``He called me and said, `I think this is the right thing to do.'''

Campaign Tour

Casey will join Obama for part of a six-day bus tour through Pennsylvania. He said he called Clinton last night to tell her of his decision.

``She was very gracious,'' Casey said. ``We know she's a great Democrat and leader. One thing we all agree on is that in 2008 we are going to elect a Democrat.''

Casey has a strong base among white, working-class voters who are liberal on economic issues yet oppose abortion rights and support gun owners' rights.

While Clinton, 60, a New York senator, is favored to win Pennsylvania, some of the state's superdelegates -- elected officials who get an automatic vote on the party presidential nomination regardless of the primary's outcome -- are remaining on the sidelines as they determine whether Obama, 46, might prove a stronger draw in November.

Status of the Race

Nathaniel Persily, a professor of political science and election law at Columbia Law School in New York, said that while Casey probably won't greatly affect Obama's chances in the primary, it may be a sign of where the nomination race stands.

``It's extremely unlikely that Barack Obama is going to win or even get very close in Pennsylvania,'' Persily said. ``Casey's endorsement is more an indication of the movement of superdelegates and other members of the party.''

Obama leads Clinton in the number of pledged delegates awarded in primaries and caucuses by 1,406 to 1,249, according to a tally by the Associated Press. Neither candidate is likely to end up with enough pledged delegates to secure the nomination after the last contest in June. That will leave the nomination in the hands of the party's almost 800 superdelegates.

Democratic National Committee Chairman Howard Dean said today on CBS's ``Early Show'' that he wants the undecided superdelegates to make up their minds ``between now and the 1st of July so we don't have to take this into the convention.''

Pressure to Quit

Democratic Senator Patrick Leahy of Vermont, who endorsed Obama in January, said on Vermont Public Radio that Clinton should quit her campaign for the good of the party.

``She ought to withdraw and she ought to be backing Senator Obama,'' Leahy said.

The former first lady is telling voters that she plans to fight for the nomination to the end.

``Some people have been saying we should just end these primaries,'' Clinton said yesterday in Winston-Salem, North Carolina, to screams of ``no'' from the crowd. ``I think a lot of people still want their voices heard.''

Clinton looked past Pennsylvania today, campaigning in Indiana and focusing on the economy in a state that has lost more than 100,000 manufacturing jobs since President George W. Bush took office in 2001.

``I would be a strong partner and a champion for manufacturing in Indiana,'' Clinton told the crowd of several thousand in Mishawaka.

Clinton's appearance in Indiana stirred up a controversy after authorities in South Bend turned down her request to visit Washington High School, the South Bend Tribune reported. Mentions of Washington drew boos at Mishawaka.

The South Bend School Corp. said it decided against hosting Clinton because the event wouldn't be open to all students, might pose a security risk to students and violate a policy of not holding political events during school hours, the Tribune reported.

Indiana and North Carolina both hold their nominating contests on May 6.

To contact the reporters on this story: Kim Chipman in Philadelphia at kchipman@bloomberg.net; Kristin Jensen in Mishawaka, Indiana, at kjensen@bloomberg.net

Last Updated: March 28, 2008 16:35 EDT