The Senate’s 79-14 vote Thursday on the Water Resources Development Act was the first veto override of the Bush presidency.

Many presidents more popular than this one have arrived at lame-duck status by this point in their incumbencies. Bush now knows that the Republican cohorts on Capitol Hill have ceased to be his. He cannot count on them to back him, even though they still do on many issues.

One cannot know what bill, if any, might produce a second override, but having broken ranks with Bush once, GOP lawmakers will find it easier to do again.

It is interesting to look at the override not merely as a precedent — the big first step — but rather as the culmination of a more intriguing and less familiar process. It was a process deftly manipulated by the Democratic majority controlling Congress.

The water bill was vetoed and the veto was overridden not at the outset of a legislative phase but at its conclusion.

The bill itself was ready for the president weeks ago, with big majorities in favor of its $23 billion worth of projects.

(There is a bipartisan taste for bills that bring federal money and jobs to congressional districts.)

But the water bill was not the only piece of legislation for which there were substantial majorities in both chambers and on which a veto override was possible.

The other was the State Children’s Health Insurance Program (SCHIP), and Congress and the administration spent weeks fighting over it. House Speaker Nancy Pelosi (D-Calif.) and Senate Majority Leader Harry Reid (D-Nev.) very deliberately decided to undertake the much tougher challenge of getting SCHIP renewal enacted before turning to the much easier task of brushing the president aside on the water bill.

Which bill was more likely to attract public sympathy — water or children’s health? Hmmm — not difficult for Pelosi and Reid to answer. So they engaged their political enemies on SCHIP first, knowing it would be a long fight generating weeks of bad PR for Republicans preaching fiscal responsibility. And in the end, if they could not override the veto, they could bring in the water bill for a swift smack-down of the beleaguered executive.

If the Democrats had done the water bill first, the memory of the override would have been buried beneath weeks of battle that ended in presidential victory on SCHIP.

But, using the water bill as their ace in the hole, the Democrats instead secured an easy victory at the conclusion of a long fight that leaves Republicans nursing their SCHIP black eyes.

The Democrats may not have been right about how much taxpayer money should be spent expanding children’s health insurance and paying for water projects all over the nation; both bills came with hefty price tags. However, being right is not the same thing as being clever, and the majority party was certainly clever in its congressional tactics.