Steven Spielberg is ready to embark on his long-in-the-works biopic of Abraham Lincoln.

Spielberg has begun discussions with Liam Neeson to play the president as he steers the North to victory in the Civil War. The plan is to start production next January, sources said.

Spielberg won’t complete principal photography on “War of the Worlds” until late March. Post-production will be rigorous, as he and star Tom Cruise gear for a late-June release.

Spielberg has wanted to make a movie about Lincoln since 2001, when DreamWorks bought rights to a bio being written by Pulitzer Prize-winning historian Doris Kearns Goodwin. That book, expected then to be published by Simon & Schuster in 2003, will finally be published next fall, under the title “The Uniter: The Genius of Abraham Lincoln.” The most recent screenwriter on the Lincoln script is Paul Webb.

Neeson, who is nominated for a Golden Globe for “Kinsey,” earned an Oscar nomination for playing Oskar Schindler in Spielberg’s “Schindler’s List.” He appears in the upcoming Ridley Scott-directed “Kingdom of Heaven” and the Chris Nolan-helmed “Batman Begins.”

A spokesman for Spielberg refused to confirm the director had made any definite decisions on the movie’s casting or when it would start. If Spielberg is indeed eyeing a January 2006 start, that would delay further his long-planned film about the aftermath of the 1972 Munich Olympics, where members of the Israeli team were held hostage and slain by Palestinian terrorists.

Spielberg, who set up that project as a co-production between DreamWorks and Universal, has pushed it back twice. The most recent postponement came after he’d cast Eric Bana in the lead role, but then decided not to start production late last summer. Instead, he hired “Angels in America” playwright Tony Kushner to do a major script overhaul.

One day later, he and Cruise decided to drop everything and do their remake of “War of the Worlds” for Paramount and DreamWorks.