The West Wing ended its seven-season run in 2006, but its legacy of political drama walk-and-talks endures. Part of the show's charm and success is due to the beloved character of Sam Seaborn, played by Rob Lowe. Despite his charisma, Lowe left The West Wing in Season 4 following salary disagreements and the diminishing size of his role.

Lowe played Deputy Communications Director Sam Seaborn, a standout character during the first four seasons. Initially intended to be the series' primary protagonist, Sam was a principled speechwriter whose rigid morality and belief in the best of people sometimes got him into trouble.

Related: Why The West Wing Ended With Season 7

A Salary Dispute Fueled Rob Lowe's Exit From The West Wing

Rob Lowe as Sam Seaborn on The West Wing

Lowe's departure from The West Wing was fueled by a number of behind-the-scenes factors, most notably money. While Lowe was originally paid more than many of his co-stars, he wasn't granted a raise when others were. Martin Sheen, who portrayed President Bartlet, negotiated a raise that nearly quadrupled his salary, while the rest of the actors who played senior staff members more than doubled their initial salaries.

Although sources say The West Wing executives would have considered raising Lowe's salary if he had been willing to wait a year, this slight likely contributed to Lowe's decision to leave.

Rob Lowe's Role on The West Wing Had Diminished

The West Wing cast in the Oval Office

Another reason for Lowe's departure was his character's diminished role on The West Wing. While Sam began as the lead character -- much of the series premiere focused on his exploits -- other characters had grown in popularity, and eventually eclipsed Sam. Losing the limelight to other characters may also have contributed to Lowe's decision to leave the show.

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Despite these behind-the-scenes conflicts, Lowe expressed nothing but love for The West Wing. In a statement about his decision to leave, Lowe described feeling lucky to depart the show in the same manner in which he arrived: "grateful for it, happy to have been on it and proud of it." His co-stars were similarly sad to see him go. According to Sheen, his colleagues were heartbroken over the loss. Regardless of any animosity over his salary, it seems that Lowe had truly bonded with the other actors and that he was genuinely missed.

Lowe's departure was written into the fourth season of The West Wing, when Sam decided to run for Congress in a special election in his home district. Sam's campaign reduced Lowe's role in the fourth season, and paved the way for his disappearance from the series.

His character did, however, return for The West Wing's seventh, and final, season, to rejoin his friends in the administration of Jeb Bartlet's successor, Matt Santos (Jimmy Smits). The created nice bookend for Sam Seaborn, and provided further evidence that, despite his departure, Lowe still loved the show.