The 1978 congressional campaign gets underway on a bleak note for Republican hopes Nov. 7. If the elections for the House were being held now; political composition would remain solidly Democratic.

Gallup surveys show the Democratic party leading in nationwide popular support. 57 to 43 percent, assuming a level of turnout comparable to 1970 and 1974, the last two previous mid-term elections. The current reading is the same as the actual division of the popular vote for members of the House in the 1976 elections.

While current results are a carbon copy of the 1976 congressional election vote, the GOP is in somewhat better shape today than a year ago. An early October 1977 survey showed the Democrats with 61 percent of the national popular vote for Congress, compared to 39 percent for the Republicans.

Present indications are that if the congressional elections were being held today, the GOP would gain few, if any seats - or, in any case, the change would be below the average gain for the "out party" of 30 to 35 seats.

President Carter's relatively low popularity rating (39 percent approval) appears to be having little adverse effect on Democratic congressional strength, contrary to the pattern observed since the beginning of scientific polling in the mid-'30s.

Typically, when a president's popularity falls below the 50 percent line, the party in power loses more than the normal 30 to 35 seats.

A key reason for the GOP's failure to gain ground in the congressional race thus far is the fact that the Republicans have yet to persuade the electorate they can do a better job on the issues voters consider most important.

A recent Gallup survey showed voters, by nearly 2 to 1, holding the view that Democratic Party is better able than the GOP to handle the problems they consider most vital to the nation. The key problems named by the public are inflation (by 60 percent) and unemployment (by 14 percent).

Not only has the GOP failed to gain the advantage on basic issues but also trail on an issue on which Republicans have traditionally held the lead over their Democratic rivals - that of reducing federal spending. A recent survey showed 24 percent saying the GOP is better able to reduce federal spending, but 28 percent crediting the Democratic Party on this issue.

The current vote also indicates the GOP will not make much headway in turning the South into a two-party region at the congressional level. If the current figures hold, Democrats in the South will win 66 percent of the cans. Outside the South the vote is much closer - 55-45 percent - but still solidly Democratic.