THE HOUSE of Representatives is making progress in solving what some of its members consider a nettlesome problem. We say some because not all of them are convinced that TV networks' projections in presidential races while polls are open on the West Coast make any difference in other races. There is anecdotal evidence that people left voter lines in 1980 when the networks accurately projected Ronald Reagan's victory over Jimmy Carter at 5:15 p.m. Pacific time. But there's no reliable evidence that those who left the lines would have made a difference even in the close races in which several veteran Democratic congressmen were beaten. No candidate has a constitutional right to votes from citizens too apathetic to wait in line.

Still, it somehow injures the notion of common citizenship for voters in one part of the country to have reason to believe that a presidential election is settled before they can have their say. The injury is nowhere near great enough to justify infringements of the constitutionally protected right to disseminate news. Proposals carelessly tossed off by some politicians to prohibit broadcasting of exit-poll results run up against the First Amendment, as do state laws that bar access to voters outside the polling place in order to prevent exit polling altogether.

Fortunately, Reps. Al Swift (D-Wash.) and Bill Thomas (R-Calif.) have taken another, more constructive approach. Their bill, as reported out of the House Administration Committee, has a jerry- built appearance to it. It provides for a uniform poll-closing time in the 48 contiguous states, at 9 p.m. Eastern time, 8 p.m. Central. In order to give West Coast voters more time to vote, it extends Daylight Savings Time two extra weeks in the Pacific time zone, so that the polls will close at 7 p.m. in California, Oregon, and Washington. Alaska and Hawaii are left alone, which is evidently their wish. Since the networks have always had a policy of not announcing the result or projecting a winner in a particular state until most of its polls are closed, they will not make any projections until the polls are closed in 48 states.

There will be some objections, notably from airlines that must juggle their schedules for two weeks every four years when the West Coast is on daylight time and the rest of the nation isn't. A solution to this problem seems well within the capacity of an industry with the ingenuity to administer frequent-flyer and multiple-discount plans.

The Swift-Thomas bill is not ideal. But it seems a reasonable and minimally disruptive response to a problem that troubles some people and is capable of inspiring far worse ideas.