This marks a sharp departure from just last month, when the revelation that Rove and presidential counselor Dan Bartlett had received subpoenas informing them they may be called as part of Libby's defense presentation sparked a flurry of news reports suggesting the White House aides would be forced to provide testimony that was politically-damaging to the president.

Libby's defense attorneys refused to comment on whether Rove will be called. There is a gag order on the case imposed on the lawyers on all sides by Judge Reggie Walton.

But Rove's legal team has been told at this point not to expect him to be called, sources told CNN, although it is still possible Libby's defense attorneys will change their minds and call him to the stand.

And one source close to Rove said the White House official has been told that his chances of being called as a defense witness are between "zero and nil" at this point.

Rove's role in the investigation of who leaked the name of Valerie Plame Wilson more than three years ago is key since he is one of the officials who confirmed her identity to syndicated columnist Robert Novak, who could testify at trial on Monday.

Initially the White House in the fall of 2003 denied Rove had any role in outing the CIA operative. The White House only later gave reporters the same denial regarding Libby.

Defense attorney Ted Wells charged in his opening statement that Libby had been a scapegoat for the White House regarding the investigation because Rove was seen as instrumental in the White House political operation.

Libby, the former chief of staff to Vice President Cheney, is charged with perjury, making false statements and obstructing an investigation. At this point, it is unclear whether either the vice president or Libby will testify.

-- CNN's Ed Henry and Kevin Bohn