The fourth season of the American political drama television series The West Wing aired in the United States on NBC from September 25, 2002 to May 14, 2003 and consisted of 23 episodes.

[2] Rob Lowe departed the series after episode 17, saying he was not happy with his character Sam Seaborn and believed he did not fit in the show anymore.

[3] On December 11, 2015, in an interview with the Archive of American Television, producer John Wells said that Sorkin was unhappy with two of the cast members, and wanted one in particular removed from the show.

As the season progressed, with ratings cresting and episodes consistently going over-budget, Wells told Sorkin he would have to be more responsive to the demands of the network and the studio.

When a meeting with Warner Bros. executives, backed by NBC, was held at the end of the season, Sorkin declined to make any changes to the way he worked, and quit the show.

The season begins with the continuation of the election storyline with the president touring the nation and his staff trying to firm up presidential debates.

Other plots include Sam leaving the White House to run in a special election in California, the news of the Abdul Shareef assassination resonating both inside and outside the U.S., Will Bailey taking Sam's position after coming over from the California campaign's staff, the President and his staff facing the reality of an overseas genocide, and Vice President Hoynes being forced to resign after a sex scandal is uncovered.

Since no one had been nominated to replace Hoynes, the presidency passes to the iron-willed conservative Republican Speaker of the House, Glen Allen Walken.

Leo is informed that Qumar has reopened the investigation into the death of its defense minister, Abdul ibn Shareef.

In a stop in a hotel bar on their way back to the White House, Donna, Josh and Toby meet a man who is struggling with the thought of paying for his daughter's education.

Senator Howard Stackhouse considers a third party candidacy, leading Josh to accuse him of potentially stealing "the President's votes".

This episode is notable as a change of pace from the typical West Wing format, as it focuses solely on one character's home life and does not touch upon operations at the White House.

and Will try to keep the press in the dark, and the President works on the drug war via the issue of certifying Colombia's worthiness as a partner in it.

On his first day at work, new Associate Counsel Joe Quincy (Matthew Perry) uncovers a scandal of mammoth proportions, sending shockwaves through the administration.

A late night party turns tragic when a Secret Service agent is found dead and Zoey Bartlet missing.

The First Family is reeling in the wake of Zoey's abduction, leading the First Lady to be sedated and the President to doubt his ability to make decisions clearly.

[29] Thomas Del Ruth received a nomination from the American Society of Cinematographers for the episode "Holy Night".