AS OF yesterday, America has a U.N. ambassador. This is a bit of a novelty, since for the past year the country's political machinery has ensured that there was none: Richard Holbrooke's confirmation was held up first by an empty ethics charge and then by various senators for reasons best known to themselves. The question now is whether Mr. Holbrooke will be allowed to rebuild America's presence at the United Nations or whether more political obstructionism will make this impossible.

During its ambassador-free period, America has been voted off the United Nation's key budget committee. It has failed to mobilize the support of other governments for further reform of U.N. bureaucracy. It has been snubbed over its requests that the next U.N. session not begin on the Jewish holiday of Yom Kippur. These slights pale next to the threat that the United Nations will rescind America's voting rights in the General Assembly -- along with those of Togo and Iraq.

Mr. Holbrooke's vigor, famously deployed in the search for peace in the Balkans, may improve America's standing somewhat. But the loss of Assembly voting rights will happen automatically unless America pays $350 million of its arrears by the end of this year. President Clinton wants to do it, and the Senate has voted a bill, by a margin of 98 to 2, that would authorize the money. But Rep. Chris Smith (R-N.J.) may derail repayment by attaching antiabortion language that would draw a Clinton veto.

Mr. Smith sabotaged repayment last year and the year before. This year he has lost a few old allies, who declare that they are pro-life but pro-United Nations as well. It is now up to the Republican leadership in the House to stop Mr. Smith from pressing his issue at the expense of America's larger interests. Until America starts to repay its arrears, it has little hope of getting its way on such issues as the closure of unnecessary committees and the reduction in America's share of the organization's budget. Presented with U.S. demands, even reasonable ones, foreigners will respond, "No representation without taxation."