COULD THERE be a worse time for Congress to be considering foreign aid? Hardly. The mood is sour, the money is short. The aid bills, put off by their friends partly to spare congressmen the embarrassment of a pre-election vote, have not taken on new allure since Nov. 4. On the contrary: some of those friends would now just as soon put the burden on the incoming Reagan administration. What should be done?

One of the two key legislative items, the aid appropriation in the House, has already gone by the board in the lame duck session. In subcommittee, only the chairman, Clarence Long, was ready to risk a test on the floor. That would have opened up the bill, already pared in the request and committee states, to further cuts and -- even deadlier -- to restricting policy amendments. And all this for nothing: there was no sign the Senate was ready to act. Instead, aid will be financed, for the second straight year, by a continuing resolution. The largest item forgone by this switch, extra money for Israel, will be put on another track. This is a pretty sad way to handle important legislative business. All that can be said for it is that it limits the damage. How will Ronald Reagan do it?

In fact, President-elect Reagan does not have the luxury of waiting until next year. Even now he is being asked to lend discreet approval to a second key measure, the authorization for the World Bank's concessional lending branch, the International Development Association. Without a Reagan wink, it is feared, House Republicans may savage the Senate-passed IDA bill, which, unlike the aid appropriation, cannot be treated by a continuing resolution.

This is serious. Whatever the good reasons are to support aid -- helping people, winning friends, competing for influence, expanding markets -- they apply in force to IDA, the leading and irreplaceable development lender to the poorest of the poor. IDA is also the central mechanism by which responsibility for aid-giving is spread among other nations: the United States is the only member country that has not made its negotiated, agreed-to contribution. Every past Treasury secretary, including Messrs. Shultz, Simon and Connally, has enlisted in the effort to boost the current IDA replenishment.

If Mr. Reagan averts his gaze, or if House Republicans do not meet it, he will have to cope right away as president with the disintegration of an institution that is doing, actually doing, more than any other to steady down turmoil in the world.