They would be called as witnesses in any subsequent trial, and if their testimony were at odds with what they told the grand jury or if it were impeached by other evidence, prosecutors could bring charges of perjury or obstruction of justice.
Although Mr. Rostenkowski's prickly personality can seem bullying to his staff, sources said that he feels a sense of obligation to them.
Some who believe that Mr. Rostenkowski should accept the prosecutors' proposal say that in recent days he has given too much credence to friends who do not fully understand the weight of the government's case against him and who fail to appreciate the personal ordeal he faces in a trial or the risk he runs if convicted.
The influence that Mr. Rostenkowski has wielded on Capitol Hill has not appeared to give him an edge in the plea negotiations.
Nor have his close ties to Mr. Clinton, who appointed Mr. Rostenkowski's prosecutor -- the U.S. attorney in the capital, Eric Holder. Mr. Clinton also has retained Mr. Bennett, Mr. Rostenkowski's lawyer, to defend him in the Paula C. Jones sexual harassment case.
If anything, Mr. Rostenkowski's connections seem to have made it harder for him to win favorable terms because of the prosecutors' concern that they would appear too lenient to a powerful friend of the administration.