President Bush can lambaste the Democrats all he likes, but on the biggest issue where there is likely to be legislative action from a new Democratic Congress, Bush agrees with Nancy Pelosi and the liberal wing of the Democratic Party. They all support "cutting-and-running" from serious immigration enforcement.

On immigration, it was only the House Republicans who stood athwart the Senate and a Bush-Democratic accord on what is effectively amnesty for illegal immigrants and insisted instead on tougher border enforcement. And there might be substantially fewer of these Republicans after Nov. 7. A Pelosi speakership could represent the final breakthrough for Bush's lax immigration policy, which was first forestalled by the 9/11 terror attacks and then by the opposition of conservatives in the House.

This election, therefore, is about amnesty as much as it is about Iraq or taxes. There are limits to how much a Democratic congressional majority could directly affect Iraq policy, and Bush would veto any tax increases. It is immigration where there could be real action. This is why conservative writer David Frum long ago suggested a rallying cry for House Republicans trying to save their majority: "Stop the Bush amnesty plan -- vote Republican."

It is obvious that the issue of immigration enforcement has resonance. Democrats have taken a pass on immigration, shrewdly staying silent on the issue in their announced package of minimalist policy initiatives should they win the House (even though not long ago their leadership was vocal in support of amnesty). But their candidates are happy to talk about it on the stump, so long as they sound as tough as or tougher than Republicans.

In Arizona's 8th Congressional District, Republican candidate Randy Graf is nearly monomaniacal on enforcement. But his opponent, Democrat Gabby Giffords, doesn't want to be outdone. She supports a guest-worker program, but rarely talks about it. She prefers to emphasize "radar, aerial drones and electronic surveillance" at the border, "tough employer sanctions" and denying government benefits to illegals.

"I have not heard anyone run on the Senate bill," says immigration expert Rosemary Jenks of the group NumbersUSA, referring to the quasi-amnesty passed by the Senate -- with more Democratic than Republican votes -- and endorsed by Bush.

For all the talk of how cynical the White House operation is, on immigration it has hurt the GOP in pursuit of what Bush (mistakenly) considers the humane and sensible long-term policy. So the president divided and dispirited his party all year long on the issue; resisted flipping to an enforcement-first position, even when it was clear that was where the wind was blowing; and now exacts an enormous opportunity cost in his inability to hit Democrats.

If they win only a slim majority, House Democrats might not be able to join Bush in passing an amnesty. Roughly two dozen House Democrats have tilted strongly toward enforcement in recent years, and the new Democrats from conservative districts will do the same. But if the Democrats rack up a sizable majority on election night, they will have more flexibility. There will be an ungainly but powerful coalition consisting of Bush, many Senate Republicans, business groups, ethnic lobbies and elite opinion all pushing toward a "comprehensive approach," the euphemism for allowing illegals currently here to stay and bringing in large numbers of their compatriots in the future.

In this case, the immigration debate will have run its usual course. The public, which overwhelmingly supports enhanced enforcement, will get the symbolism: The 700 miles of border fence of the Secure Fence Act, which may or may not get built, depending on the commitment of the (unenthusiastic) Bush administration and Congress going forward. But the forces supporting yet another increase in levels of immigration will get the policy, in some form of "comprehensive" reform.

There is only one way to ensure that this won't happen, and it is to retain a Republican majority in the House that, for all its flaws, acted on this issue with foresight and courage.