PROGRESS REPORT: The foreign-aid bill is now halfway through the House, and the votes are better, so far, than we had expected. The balance of forces is still extremely close, but it seems to have shifted slightly over the summer in favor of the principle of foreign aid.

The line of attack on foreign aid is no longer simply to cut the amounts of money in the bills. Momentum has built up behind a large family of destructive proposals with, superficially, a broad political appeal. Some of them invoke the rhetoric of the human-rights campaign, and some of them talk about the preservation of American markets. All of them, in one degree or another, would diminish the effectiveness of American aid abroad.

A preliminary test came in late July, when the House took up the bill to expand the Export-Import Bank's lending authority. The bank is a government agency that promotes American exports with subsidized loans to foreign buyers. It doesn't have much to do with foreign aid, but it got swept up in foreign-aid politics. The most dangerous assault on it was a protectionist amendment drafted by Rep. Clarence D. Long (D-Md.), prohibiting loans to produce abroad any commodity that might be "in surplus" - that is, in competition with American goods. The Long amendment was beaten by a hairbreadth, 199 votes to 197. Then came the other perennial, the attempt by Rep. Thomas R. Harkin (D-Iowa) to prohibit Ex-Im Bank loans to countries violating human rights, unless the loans should "directly" benefit the poor. The Harkin amendment enjoyed a considerable vogue last year, but as good may congressmen have come to perceive that vaguely worded riders on economic legislation are a bad way to protect anybody's human rights. This time it got beaten soundly, nearly 3 to 1.

Last week the Senate took up the bill to authorize an American contribution of $1.8 billion to the International Monetary Fund for loans to countries that need help paying their oil bills. Human-rights restrictions would be even less effective here than in the Ex-Im Bank bill. But, characteristically, Sen. James Abourzek (D-S.D.) tried to attach a Harkin-style amendment. It was beaten, and the bill passed.

Then the foreign-aid appropriations bill came to the floor of the House - the most important, and the most vulnerable, of these three bills. The threat of restrictive amendments is particularly dangerous here, because the bill carries the money for the World Bank and the other international lending agencies. The will not accept money with political strings tied to it, and without American leadership this valuable international effort is not likely to survive long.

Part of the unexpected success so far is due to extremely competent floor management by Reps. David R. Obey (D-Wis.), Silvio O. Conte (R-Mass.), Charles Wilson (D-Tex.) and Matthew F. McHugh (D-N.Y.). part of its due to the Carter administration, which for once, has lobbied with vigor and skill. Part of it is the work of a wide range of economic interests, from labor unions to the U.S. Chamber of Commerce, reminding the doubters in Congress that foreign trade and aid equals jobs here at home.

The outcome is anything but certain. Yet these challenges serve at least one useful purpose: They have required Congress to think carefully about that much-neglected subject, foreign aid. The principle of aid is suddenly being defended, by the administration and in Congres, with unexpected force.