AN EIGHTH and final cloture vote on battered S.2, the bill to limit congressional campaign spending, is set for today. The filibustering Republicans will win again; the Democrats have the votes to pass the bill but not the 60 needed to choke off debate. The matter goes over to the next Congress.

It's important to remember what this vote is about. It's not about the parliamentary jostling that did indeed turn a little ugly up there Tuesday night. The Democrats were unable to maintain a quorum they needed for procedural reasons; their clumsy response was to issue arrest warrants for the Republicans who, for the same procedural reasons, had fled. Sen. Bob Packwood was found and "arrested" in his locked office around midnight by the sergeant-at-arms, who had a pass key and forced his way in. The artful truant, who may have bruised a previously broken hand in the process, amiably returned to the Capitol with his captor, then had himself carried onto the Senate floor by two Capitol policemen.

Mr. Packwood said good-humoredly the next day that he "rather enjoyed" the whole thing, but other Republicans used it to change the subject. The issue ceased to be campaign finance, their party position on which makes some Republicans uncomfortable. Instead it became a procedural offense, a thicket and refuge every senator quickly learns to love. "The knock on the door and the forced entry smack of Nazi Germany, smack of Communist Russia," Sen. Arlen Specter declared. We know it's early in the year to be grabbing awards, but if this doesn't retire the 1988 prize for self-pity and self-dramatization, we don't know what will. You have to wonder what Sen. Specter would say if something really awful happened.

The vote today is about the role of money in congressional affairs. A certain amount of money in democratic politics is healthy; too much is corrupting. There is too much now. In the period from 1976 to 1986, the cost of living nearly doubled. In that same period, congressional campaign expenditures nearly quadrupled. Senate candidates in 1976 spent $38 million; the average winner spent $600,000. Five election cycles later, the candidates spent $179 million; the cost of a Senate seat had become $3 million. To raise the money he will need for reelection, the average senator now has to raise $10,000 a week every week of his six-year term. If he comes from a large state or fears a close election, he may have to raise four times that. They already live with their hands out. Where can it end?

The Democrats seek to impose spending limits. Everything else about their bill, including where first to set the limits (they would be indexed thereafter), has been negotiable, as every senator has understood. But the willing Republicans have been whipped away from the bargaining table by others who say unlimited spending is the only way their party can thrive. The rational Republicans have been cowed by their more vehement colleagues. The buying of the Senate goes on.