SHOULD SENATORS be paid by the taxpayers who hire them or by lobbying groups that have their own special interests? That is an issue scheduled to come before the Senate soon, when it votes on an amendment by Sen. Henry Jackson (D-Wash.) to the supplemental appropriations bill. The amendment would bring Senate pay in line with that of the House of Representatives: senators' salaries would be raised from $60,662 to $69,800, but the amount of outside income they could earn would be limited to 30 percent of the salary. Currently, there is no limit on senators' outside income, and some senators get a sizable percentage of their income--in some cases, more than half--in fees from organizations almost all of which have interests in legislation.

This is a seamy situation. It is out of line with historical practice for the two houses to be paid differently. And the importance of honoraria to many senators creates the impression of undue influence and the suspicion that legislative decisions are up for auction. Some senators argue, plausibly, that they need more money; but the right way for them to earn it is by straightforwardly raising their salary. To those senators who think that is politically dangerous, we commend the example of the House, which voted for a pay raise last December even though all its members must seek reelection every two years.

In the long run the only way for members of Congress to keep their salaries reasonably in line with their needs and with inflation is to get in the habit of voting, year after year, for reasonable pay increases. That is surely less dangerous politically than the spectacle of senators' deriving large proportions of their income from people pushing legislation.

Sen. Jackson also has a fallback amendment; it would give each senator an option: accept a 30 percent ceiling on honoraria but get the salary increase, or accept unlimited honoraria but no salary increase. This would make each senator directly accountable to the voters for his choice. But it is one of those solutions that complicate rather than simplify the problem. The spectacle of some members of Congress earning large sums from lobbying organizations would still be there, and in the hurly-burly of campaigns would tend to harm all members. The better solution is the simpler one: the Senate should show the same political courage the House did by limiting outside earnings and raising the salary to a reasonable level.