Republican contacts on the Hill tell me there is no sign thus far of a White House campaign to sustain the farm bill veto the Bush administration has been talking up for months now, most recently on Friday's press call with Agriculture Secretary Shafer and Deputy Chuck Conner.

The absence of an active White House presence on the issue, up to and including indications that the president and vice president will weigh in personally, has caused Republicans to wonder how serious the White House really is about winning the farm bill veto fight.

There's not much time left for the White House to demonstrate resolve. With splits within the House Republican leadership on the farm bill--Minority Leader John Boehner in opposition to the measure and GOP Conference Chair Adam Putnam cheering for passage--it will take a full-court press by the White House lobbying apparatus to win a veto showdown. Statements from the podium of the White House press room or USDA's leaders, however clear and firm, won't be enough.

UPDATE MONDAY 2:10 PM: Boehner raises "earmark" objections to farm bill in this op-ed but doesn't even mention the impending veto.

Without a strong and visible White House push in the next three days inside the House Republican Conference, insiders warn, by the time the override vote is eventually taken Bush may already have lost.

The calculation is very simple. With the farm bill going to the House Rules Committee at COB this Tuesday, the measure may come to the floor as early as Wednesday. The sooner the better for supporters of the bill, who feel they have the momentum and want to run up the score with a big vote for passage this week.

There's no question the farm bill will pass the House. The question is whether a bloc of one-third of those present will either vote against the bill, or at least register as "not voting" and thus plausibly be deemed to be on the fence. A Republican "Nay" plus "NV" tally of one-third or more of the House, bolstered by some Democrats voting against the bill, would strongly indicate the president's veto can be sustained.

The White House would surely prefer a one-third "nay" vote. But "not voting" could emerge as an attractive outlet for GOP members who want to signal support for the president and his objections to the farm bill. That outcome would at minimum prolong the suspense about the outcome of the veto override, giving the White House more time and political room to build support.

(Not many Democrats are likely to vote no or take the "NV" option, unless they are willing to buck Speaker Pelosi and give Blue Dogs some payback for derailing last week's war supplemental vote. But a show of discord on the Democratic side could become a premise for the Speaker to pursue her wish for more subsidy reform, presuming that is indeed her wish.)

But it will be next to impossible to convince Republicans who vote for passage of the farm bill this week to turn around and sustain the president's veto of the same measure days later. A lop-sided win for the subsidy lobby on passage this week comfortably above two-thirds of the House (291 if every member votes) would make the veto override vote ceremonial only, and of questionable help in Republican efforts to unite, show strength and restore their brand. That's a "why bother" scenario for many Republicans.

However, if it is clear from this week's House vote that a veto will be or is likely to be sustained--and if in the event it is sustained--Agriculture Secretary Schafer and Deputy Secretary Conner will have the leverage they need to press for further subsidy reforms and other items on the administration's wish list.

That leverage will be substantial. Speaker Pelosi can't push a naked extension of the discredited 2002 farm bill through her own caucus much less the whole House. Even the fig leaf of phony subsidy reforms now in the bill would be gone, and there would be no increase in food assistance or conservation funds, no Pigford relief for black farmers, none of the tax blandishments Chairman Rangel secured for the Caribbean . . . and on and on.

But the game's over if the White House allows the veto override to look inevitable after this week's House vote.