MOVIE REVIEW : Mr. Murphy Goes to Washington : When showcasing his comic gifts, Eddie Murphy turns his latest film into the funniest one he’s made in a long time.

Like the hapless U.S. Congress, the unwieldy institution it lampoons, “The Distinguished Gentleman” (citywide) is a creature of compromise. It tries to find what common ground it can between two different sides of Eddie Murphy, as well as reconcile a pair of dissimilar story lines. While the result is inevitably middle of the road, it still manages to be the funniest picture Murphy has made in quite some time.

For when Murphy allows himself to be flat-out funny, there is no room for argument. A master of dissimulation and disguise, with a gift for mimicry that ranges across all ethnic boundaries, Murphy is perfectly at home in the role of Florida con artist Thomas Jefferson Johnson. Johnson is the man behind television spots for a scam called Girls of Many Nations, which is really an excuse for himself, his cousin Loretta (Sheryl Lee Ralph) and the rest of their amiable gang to fleece unsuspecting marks.

Hiding from an outraged target at a posh political gathering, Johnson overhears a congressman and one of his supporters talk about the whole range of perfectly legal perks, both financial and otherwise, that being in the House seems to guarantee. “I am definitely in the wrong business,” Johnson concludes, and fate soon helps him to change all that.

Not only does that current congressman, also named Jeff Johnson, conveniently die, but he leaves behind him a slogan (“The Name You Can Trust”) that is tailor made for the stealth campaign the still living Johnson plans to wage to con himself into a seat in the House.

The plot to get to Washington is the film’s loosest and most consistently amusing part. It allows Murphy to do a variety of expert comic impersonations, everything from an old Jewish man to a buttoned-down academic from Wilson Pickett State Teachers College. And it makes good use of director Jonathan Lynn (“My Cousin Vinny” and the British “Yes, Minister” series) who is an able facilitator of light farce material.

Once Johnson gets to Congress, things change. Screenwriter Marty Kaplan, a former chiefspeechwriter for Walter Mondale, knows the political system inside out, and one of his goals for “The Distinguished Gentleman” (rated R for language and a scene of sexuality) is to graft a satirical expose of loopholes and malfeasance onto what has been to that point pretty much of a slapstick farce.

So new Congressman Johnson meets cash-rich lobbyists like Terry Corrigan (Kevin McCarthy) and powerful politicians like Dick Dodge (Richard Nixon lookalike Lane Smith) who always seem to have their hands out. He finds out about PAC money and the generous honoraria to be had for saying a few words at breakfast. Whenever he thinks he’s onto a hot scam, it turns out to be business as usual on Capitol Hill. “All this money from both sides, how can anything get done?” he wonders. “It doesn’t,” Corrigan replies affably. “That’s the genius of the system.”

This stuff is all too true and amusing as well, but, not being on the same wavelength as the knockabout stuff, feels like it comes from a different movie. The same is true for the squeaky-clean romance Johnson (Murphy in the Cary Grant mode he has taken a liking to) has with public-interest lobbyist Celia Kirby (“The Young and the Restless’ ” Victoria Rowell).

Hardest of all to digest is the saccharine change of heart that Celia, her right-thinking congressman uncle (Charles S. Dutton) and some teary constituents make in Johnson, turning him from a sinner to a saint in no more time than it takes to say amen . This

turn of events, though inevitable, is more lachrymose than convincing and performed as if the actors themselves found it embarrassingly hard to believe.

But even though the confident wisecracking persona that audiences love has to fight for space with the suave leading man the actor himself seems to prefer, “The Distinguished Gentleman” never forgets which side its bread is buttered on and Eddie Murphy isn’t allowed to go too long between laughs. And, after all, isn’t the essence of political compromise that no one gets everything they want?

‘The Distinguished Gentleman’

Eddie Murphy: Thomas Jefferson Johnson

Lane Smith: Dick Dodge

Sheryl Lee Ralph: Miss Loretta

Joe Don Baker: Olaf Andersen

Victoria Rowell: Celia Kirby

Grant Shaud: Arthur Reinhardt

Kevin McCarthy: Terry Corrigan

A Leonard Goldberg production, in association with Touchwood Pacific Partners I, released by Hollywood Pictures. Director Jonathan Lynn. Producers Leonard Goldberg, Michael Peyser. Executive producer Marty Kaplan. Screenplay Marty Kaplan, story by Marty Kaplan and Jonathan Reynolds. Cinematographer Gabriel Beristain. Editor Tony Lombardo. Costumes Francine Jamison-Tanchuck. Music Randy Edelman. Production design Leslie Dilley. Art director Ed Verreaux. Set decorator Dorree Cooper. Running time: 1 hour, 51 minutes.

MPAA-rated R (language and a scene of sexuality).