The vote in the judiciary committee of the House of Representatives on Monday night set the impeachment process irrevocably in train. After hours of forcing amendments to the vote and losing, the 16 Democrats accepted the inevitable and allowed the vote on the main resolution - to advance or not to further investigation of President Clinton - to proceed, open- ended in time and not restricted to the Monica Lewinsky affair.
The full House is to debate and vote on the resolution tomorrow, or on Friday, but the outcome is certain. The only doubt is how many of the 206 House Democrats will cross the floor to vote with the Republicans. Estimates range from a bare 30 to 100.
The determining factors are less individual conscience than the Representatives' assessment of opinion among the voters back home who will decide on their re-election to Congress at the mid-term elections in less than four weeks' time.
Those not running for re-election have already been more outspoken in their criticism of Mr Clinton than those who depend on the party for campaign funds. But constituency polling of voter opinion is in full swing, and surprises cannot be excluded.
Yesterday, Jerome Zeifman, a Democrat elder statesman who was chief counsel of the House judiciary committee at the time of the Nixon impeachment hearings, issued an appeal to fellow Democrats in the anti-Clinton Wall St Journal. "I believe I have a personal responsibility to speak out about the current impeachment crisis," he said. "I believe my fellow Democrats on today's judiciary committee have a moral, ethical and constitutional responsibility to vote to impeach President Clinton." The positions taken by the President and his Democratic defenders, he said, were "indefensible".
In the tense waiting period between the judiciary committee vote and the vote in the full House, the White House was strangely reticent, at least in public. "I think the American public has a right to be disappointed," said Joe Lockhart, the new spokesman, of Monday night's vote, which split strictly along party lines.
Hinting at the line likely to be taken by the White House in coming weeks, he accused the Republican leadership of "pursuing a strategy for electoral advantage'' - in other words placing party political interests above the high judicial considerations that American politicians always claim underlie an impeachment in- quiry. In private, however, the White House was reported to be watching allegiances in Congress exceptionally closely and lobbying hard to limit the scale of Democrat defections.
In the longer term, the White House appears to be pinning its hopes on Mr Clinton's continued popular appeal.
It is optimistic that if Democratic support holds up well in next month's elections, the appetite for impeachment among the President's opponents will faded.
In that case, Mr Clinton could hope to have the impeachment inquiry concluded rapidly and escape with a vote of censure.
The risk in that strategy is that if the Democrats, including candidates who have defended the President, lose heavily, Republican representation in the House (and on the judiciary committee) increases, and the impeachment hearings drag on.
While few forecast that Senate Republicans, even after the elections, could muster the two-thirds majority necessary to impeach the President, the damage from protracted hearings to Mr Clinton's second-term programme could be considerable.