Former Pittsburgh Mayor Sophie Masloff will endorse Sen. Hillary Rodham Clinton when the New York senator appears this evening for the Allegheny County Democratic Party's Jefferson-Jackson Dinner at Heinz Field.
"It's been very difficult for me to sit on the sidelines and fail to support a woman," said Mrs. Masloff, a Democratic superdelegate who had been neutral in the presidential race. "For a long time, I was convinced I shouldn't make a public choice. We have two wonderful candidates. But finally, I just couldn't sit on the fence."
Mrs. Masloff is the second Pennsylvania superdelegate to move into the Clinton column in recent weeks. Rep. Jack Murtha, D-Johnstown, the dean of the state's congressional delegation, announced his support for Mrs. Clinton last month.
The popular former mayor's decision will be doubly welcome for the Clinton camp because most of the traffic in superdelegates has gone in the other direction recently. Superdelegates, free to vote their personal preferences at the national party's nominating convention next fall in Denver, are key to Mrs. Clinton's hopes of overtaking Illinois Sen. Barack Obama.
Mrs. Clinton maintains the lead she has held in the superdelegate category since before the Iowa caucuses Jan. 3, but it has been narrowed over time by the steady trickle of endorsements for Mr. Obama.
His biggest Pennsylvania acquisition in that coveted category was U.S. Sen. Bob Casey, who announced his surprising support for Mr. Obama two weeks ago. Still, Mrs. Clinton can count on the support of most of the state's Democratic hierarchy, led by Gov. Ed Rendell, who is also expected to appear at tonight's dinner in Pittsburgh. The last time Mrs. Clinton was in the city, on St. Patrick's Day weekend, she left with the endorsements of Allegheny County Chief Executive Dan Onorato and Pittsburgh Mayor Luke Ravenstahl.
While those two are the highest-ranking local Democratic officials, they don't have quite the convention clout of Mrs. Masloff. The Grant Street neighbors are almost certain to be named to the Clinton campaign roster of pledged delegates, but -- unlike Mrs. Masloff -- they are not superdelegates, who have an automatic convention-floor ticket.
Overall nationally, according to the latest Associated Press tally, Mr. Obama leads the delegate race, by a margin of 1,638 to 1,502 before Mrs. Masloff's announcement. He has outdistanced Mrs. Clinton in delegates won in primaries and caucuses, by a margin of 1,414 to 1,250.
The former first lady had 252 superdelegates to Mr. Obama's 224 as of yesterday. Mrs. Masloff will make it 253.
It will require support from 2,025 delegates to win the party's presidential nod at the Denver convention -- a total that neither candidate will be able to reach with elected delegates alone.
Mr. Obama and Mrs. Clinton will be in Pittsburgh Monday for back-to-back appearances before the Alliance for American Manufacturing, an officially non-partisan partnership of the United Steelworkers and manufacturers including U.S. Steel and Allegheny Technologies.
Spokesman Steven Capozzola said the alliance had also invited Arizona Sen. John S. McCain, the presumptive Republican presidential nominee, but he was unable to attend because of a scheduling conflict. Mrs. Clinton and Mr. Obama are slated to appear separately at the alliance's event, which is closed to the public.
Post-Gazette politics editor James O'Toole can be reached at email@example.com or 412-263-1562.