The influential legislator is expected to appear at the Convention Center. He has told advisers that he needs to recover from a March 2 heart attack that sent him to the hospital for a week. He was released on Sunday.
In September, Fumo is scheduled to go on trial on a massive 139-count indictment charging him with defrauding taxpayers and two nonprofit organizations, and with attempting a coverup to obstruct the FBI investigation.
He is facing three opponents in the April 22 primary, including a well-financed effort from John Dougherty, the labor leader who is a bitter Fumo enemy.
A person close to the matter said that Fumo mulled the matter while in the hospital. He told advisers of his final decision last night, two days after his release.
"It's fair to say the decision was made today [Tuesday]," the person said.
Ken Snyder, a Fumo spokesman, and other Fumo aides did not respond to telephone calls seeking comment.
Shortly after the heart attack, several people close to the senator said that although Fumo was under enormous stress, they doubted he would drop out.
"He's a fighter," one person close to him said last week. "It's what he does: Vince Fumo is a state senator 24/7. It's his life."
Along with the bid by Dougherty, Fumo was to face a primary challenge from lawyer Lawrence Farnese and community activist Anne Dicker.
With his sizable war chest and army of union workers, Dougherty is viewed by many political analysts to be the likely new front-runner. However, sources have said he is under federal investigation; Dougherty has dismissed the probe, saying it will find no wrongdoing of any kind.
G. Terry Madonna, a politics professor and pollster at Franklin and Marshall College, called Fumo's decision "stunning news" but nonetheless understandable given what he is facing: a forthcoming corruption trial, health issues, and a tough primary fight.
