David has expressed his love for the US TV series "The West Wing", in the interviews below he compares Russell's writing to the style of the show.
"And the way Russell writes both characters, there's an enjoyment of language and of thought colliding with each other faster than the speed of thinking. Which I've always liked. I like that kind of writing. I'm a big fan of "The West Wing," and the way Aaron Sorkin writes those people who can think and speak faster than the synapses can flash. I love characters who are clever and smart, and you have to run to catch up with. I think there's something very appealing and rather heroic in that. So it made sense that The Doctor should be like that, to me." - talking to Alan Sepinwall in an interview with nj.com
"I think that's very attractive to watch in a character, when they're plucking all these extraordinary thoughts down and you have to race to catch up, kind of like The West Wing. Russell's a lot like that himself.'" - from December 2005 article "Tennant's Extra"
He even got a chance to show off his knowledge of the show on the BBC special "The Ultimate West Wing Challenge" which aired July 28, 2006. This is a link to a great copy of the show. Rory Bremner was the host and the quiz pitted David Tennant and Stryker McGuire against Arabella Weir and Mark Oaten. David and Stryker won!
In the BBC Radio series Chain Reaction where David was interviewed by Catherine Tate he talked about going to see Richard Schiff, who played Toby Ziegler on the show, in in Underneath the Lintel.
You can listen to him tell it here: