This follows moves to indict him on charges including rape.
Mr Katsav, who denies any wrongdoing, has faced calls from ministers and MPs for his immediate resignation from his mainly ceremonial position.
The unprecedented case is among several scandals currently affecting Israeli politicians, that are causing serious political uncertainty.
On Tuesday, Israel's attorney-general announced that Mr Katsav will be charged with offences including rape, obstruction of justice and fraud.
Under Israeli law, a parliamentary committee would have to approve any leave of absence, parliamentary spokesman Giora Pordes said.
There has been no public comment from Mr Katsav's office.
Criminal proceedings cannot begin while the president remains in office, but his seven-year term ends later in 2007.
But left-wing Knesset members have started canvassing support for an impeachment hearing in parliament.
Twenty MPs' signatures are needed for an impeachment. Ninety votes in the 120-seat body would be needed for dismissal, although this number is reportedly being reviewed.
Israel radio has reported that Mr Katsav is due to hold a news conference at 1730 GMT.
The formal indictment against Mr Katsav will only be filed after a special hearing for the president to state his case, Attorney-General Menachem Mazuz has decided.
Defence lawyers have expressed confidence that the case will be dropped at that hearing.
"It will become clear that he is the victim of trumped-up charges and a failed attempt to oust him from his position and he will fight to prove his innocence," said David Libai on Tuesday.
One of the strongest calls for resignation came from Education Minister Yuli Tamir, who said his continued presence was an "embarrassment".
"It is impossible to educate students to respect the presidential institution and ask them to hang pictures in every school of a president charged with grave offences."
Justice Minister, also Foreign Minister, Tzipi Livni, has said resignation would be "the appropriate action".
Iranian-born Mr Katsav, 60, was a journalist before standing for parliament as a candidate for the Likud party in 1977.
He was the first member of a right-wing political party to become Israeli president, beating off the challenge of Labour veteran Shimon Peres in 2000.
The office is invested with great dignity and prestige in the Israeli political system, but powers are limited. They include pardoning prisoners.Güncelleme Tarihi: 20 Eylül 2018, 18:16