Martin Sheen plays the US president in the West Wing

The seventh series will return to US screens for the 2005-2006 season, with a new president set to take his place in the White House.

Although ratings for the show have slipped in recent years it is still attracting affluent audiences sponsors want, said NBC boss Kevin Reilly.

Friends spin-off Joey has also been recommissioned for a second series.

Although ratings for the sitcom have failed to match up to Friends, NBC is keen to continue with the Matt Le Blanc vehicle.

Critical darling

Successful medical drama ER has been handed another two years, ensuring it will remain on air until at least 2008.

The West Wing has been a critical success since it began, with its ensemble cast winning numerous awards, but has not always performed well in the ratings.

The big change for the seventh season will be a new president following the end of the second term of Jed Bartlett, played by Martin Sheen.

Names in the frame include Senator Arnold Vinick, played by Alan Alda and Vice President Robert Russell, played by Gary Cole.