Neither Mike Manzo's lawyer, Jim Eisenhower, nor Kevin Harley, a spokesman for the attorney general's office, would say whether the Manzos are cooperating with prosecutors.
A phone message left for Rachel Manzo's lawyer, Bill Ward, was not immediately returned.
Defendants who are cooperating or actively seeking plea bargains often waive their preliminary hearings, but that is not the only possible motive for such a move.
The action capped a day of dramatic developments in the closely watched case, after three of the other 10 co-defendants unsuccessfully argued the proceeding should be pushed back so it would not affect the Nov. 4 election.
A one-paragraph order by Lewis said they did not offer sufficient justification and that he based his decision partly on arguments made during a conference call.
The defendants who sought the delay are former Democratic state House aides Brett Cott and Anna Marie Perretta-Rosepink, and former House Democratic Whip Mike Veon of Beaver County.
Their attorneys had argued that a "politically charged atmosphere" in the case could affect national and state elections.
"A preliminary hearing in this matter within one month of the election would ... create such great media attention to ... create 'undue influence' on voting," wrote Cynthia Reed Eddy, Perretta-Rosepink's attorney.
Eddy declined comment following Lewis' ruling except to say "the court made its ruling, and I respect that." Lawyers for Cott and Veon did not immediately return phone messages late Friday.
Senior Deputy Attorney General Anthony Krastek, the lead prosecutor, had opposed the postponement, writing in a court filing that Eddy had not offered any "legally sufficient basis" for a delay.
Eddy's assertion that publicity has influenced potential jurors is "manifestly premature," Krastek said.
The preliminary hearing, for which prosecutors have summoned 27 witnesses, is scheduled to start Tuesday and expected to take several days.
The defendants are Cott, Perretta-Rosepink, Veon, the Manzos, state Rep. Sean Ramaley of Beaver County and six other current or former employees of the House Democratic caucus.
The attorney general's office claims the defendants illegally used public resources to run political campaigns, among other allegations in a 74-page grand jury report issued in July. All face various counts of theft, conflict of interest and conspiracy.
The witness list includes Angela Bertugli, who allegedly was given a job entailing very little work because of her sexual relationship with her then-boyfriend Mike Manzo.
Also on the list are former Democratic state Rep. Frank LaGrotta of Lawrence County and Bill Chadwick, the Washington consultant who has been helping the Democrats respond to the attorney general's investigation.
Chadwick said Friday he and a former employee of his firm, Michael Levine, are on the list because of their work recovering and searching through electronic data to produce e-mails and other documents in response to prosecution subpoenas.
Thirteen of the prosecution's expected witnesses work for the House Democratic caucus. Also subpoenaed are the state Treasury Department and three investigators.