Steven Culp Steven Bradford Culp is the actor who portrayed Major Hayes in five episodes of s third season . He had previously played Commander Martin Madden , Jean - Luc Picard ' s new first officer in , but his scenes were deleted from the final film . He is perhaps best known for his roles on the television series " JAG " and " Desperate Housewives " and for his portrayal of Robert F . Kennedy in the film " Thirteen Days " . Early life . Culp was born in La Jolla , California but moved to Virginia as a child . He attended First Colonial High School in Virginia Beach and graduated from The College of William & Mary with a major in English literature . He then studied English Literature at the University of Exeter in Devon , England before studying Theater Arts & Acting at Brandeis University in Waltham , Massachusetts . Television . In 1983 and 1984 , near the start of his acting career , Culp played the regular role of Dr . Danny Wolek on the ABC soap opera " One Life to Live " . Several years later , he guest - starred on " A Man Called Hawk " , a short - lived series starring s Avery Brooks in the lead role . Culp subsequently appeared on such television programs as " Murphy Brown " ( in an episode with Janet MacLachlan ) , " L . A . Law " ( with James Avery , Corbin Bernsen , Larry Drake , Jennifer Hetrick and Diana Muldaur ) , " Touched by an Angel " ( with Jeanetta Arnette ) , and an episode of " Beverly Hills , 90210 " directed by James Darren . In 1996 , Culp won the recurring role of Special Agent Clayton Webb on the CBS series " JAG " . He appeared in 41 episodes of this series airing between January 1997 and September 2004 , making his debut in the first episode of the second season entitled " We the People " and directed by Les Landau . During his time on " JAG " , Culp continued appearing on other shows such as " Dr . Quinn , Medicine Woman " ( starring Joe Lando ) , " Profiler " , " Ally McBeal " ( with Roy Brocksmith , Kate Asner , Gina Philips , Jay Karnes and Clyde Kusatsu ) , " Boston Public " ( starring Jeri Ryan ) , and " Crossing Jordan " ( with Robert Curtis Brown , Miguel Ferrer and Paul Winfield ) . In 2003 , prior to his making his debut on " Enterprise " , he played Ted Simmons in three episodes of the hit FOX series " 24 " , working with the likes of Jude Ciccolella , Daniel Dae Kim , Michelle Forbes , Penny Johnson , and Harris Yulin . That same year , he appeared with Robert Picardo in an episode of the short - lived " The Lyon ' s Den " . From 2003 through 2005 , Culp played Speaker of the House Jeff Haffley on " The West Wing " . In 2004 , he had a recurring role as Dave Spencer on the long - running NBC series " ER " . Perhaps his best known role , however , is that of Dr . Rex Van de Kamp on the ABC ' s popular series . He was a regular on this series during its first season , alongside Teri Hatcher and Mark Moses . Rex was involved in an affair with Maisy Gibbons , played by guest star Sharon Lawrence , during which Culp ' s character suffered a heart attack , ultimately leading to his " untimely " death . Culp returned to the show for flashback scenes during the second season finale and narrated an episode from the third season . Culp later starred in the ABC drama " Traveler " , along with DS9 guest star William Sadler and actor Neal McDonough . He has also appeared on " Numb3rs " with Bruce McGill , " The Closer " with Raymond Cruz , and the Sci - Fi Channel ' s " Stargate : Atlantis " . In December 2007 , he appeared on " Boston Legal " , playing the attorney prosecuting William Shatner ' s character , Denny Crane , on soliciting charges . The episode also featured former regular Rene Auberjonois and current regular John Larroquette . More recently , he has appeared as an American Patriot officer in the series " Revolution " , co - starring Stephen Collins . Film . In addition to his television credits , Culp has appeared in several films , beginning with 1989 ' s " Gross Anatomy " ( with Gordon Clapp , Clyde Kusatsu , and Kay E . Kuter ) . Perhaps his most notable film role was that of Attorney General Robert F . Kennedy in the 2000 drama " Thirteen Days " . Bruce Greenwood , the actor who played Christopher Pike in ' s , played Kennedy ' s brother , President John F . Kennedy . Culp would again work with Greenwood on the 2007 family comedy " Firehouse Dog " . " Thirteen Days " also featured fellow " Star Trek " alumni Jack Blessing , Len Cariou , Kevin Conway , Charles Esten , Tim Kelleher , Boris Lee Krutonog , Ed Lauter , Dakin Matthews , and Bill Smitrovich . This film was actually the second time Culp played Robert Kennedy : he previously tackled the role in the 1996 HBO movie " Norma Jean & Marilyn " , which starred Ashley Judd and also featured Jeffrey Combs and John Rubinstein . Culp ' s other movie credits include " Dead Again " ( with Raymond Cruz ) , " Jason Goes to Hell : The Final Friday " ( with Leslie Jordan ) , " Fearless " ( featuring John de Lancie ) , " James and the Giant Peach " ( in which he played the title character ' s father ) , " Nurse Betty " ( alongside Kevin Rahm ) , " The Emperor ' s Club " ( with Harris Yulin ) , and " Spartan " ( with Matt Malloy and Natalia Nogulich ) . Appearances . As Martin Madden As Major J . Hayes