There is one good reason why opera companies shouldn't do operettas and musicals: they are not equipped for the style. And one good reason why they should: we wouldn't otherwise hear them. Opera North's decision to programme four musicals or operettas within a single season is therefore noteworthy. The fact that one is by Shostakovich and another by David Sawer, a contemporary English composer, does not alter the fact that Opera North - or should we say Operetta North? - is redefining its mission. Maybe it feels there are enough Carmens on its beat in the form of cheap eastern European touring outfits, and it can serve its public by creating a broader mix.

Whatever the case, the choice of the Gerswhin brothers' Of Thee I Sing, a 1931 satire on American presidential elections, was timely. The score combines dance-band doggerel, sexy syncopations and catchy tunes, with a nod to Gilbert and Sullivan (whom the Gershwins adored). The lyrics include such advice to the president as "You only make a speech when you want the stock market to go down", whereupon someone asks how he can make it go up: "Boy, would I like to know." The election becomes a beauty contest - to choose the prospective president's wife (shades of Carla Bruni) - while his running mate is satirised as a nonentity (shades of Dan Quayle).

Thanks to choruses extolling corn muffins over justice, the lack of sincerity eventually starts to grate. But the real problem is generic. With acres of spoken dialogue, Of Thee I Sing hardly needs an orchestra of the expertise of Opera North's. Nor does it require polished opera singers, which Opera North supplies - complete with American accents and English reticence. It does demand professional dancers, but a regional company doesn't do that - so the choruses get by with co-ordinated arm-waving and heel-lifting.

William Dazeley is the suave president-to-be, Bibi Heal his homey love-interest. Heather Shipp turns the beauty queen into a delicious dragonette, but the scene-stealers are Steven Beard's vice-president and Richard Suart's French ambassador. The conductor Mark Dorrell keeps the score moving along nicely, and Caroline Gawn's staging, designed by Tim Hopkins and Gabrielle Dalton, exudes period charm. A harmless evening.

On tour, www.operanorth.co.uk