The rhetoric from the Democratic candidates for president yesterday in response to the Supreme Court’s decision to uphold a federal ban on partial-birth abortion was predictable. The phrases “could not disagree more strongly,” “hard right turn,” and “erosion of our constitutional rights” figured prominently.

The official responses issued by the Big Three on the Republican side, however, offer a window into the state of the race — and into the role that abortion plays in defining the Republican Party.

The simplest of the three statements came from the campaign of a former governor of Massachusetts, Mitt Romney: “Today, our nation’s highest court reaffirmed the value of life in America by upholding a ban on a practice that offends basic human decency. This decision represents a step forward in protecting the weakest and most innocent among us.”

The statement was short and to the point. What’s more, it projected confidence. Despite his pro-choice history and recent “conversion” on abortion, Mr. Romney has been trying to position himself as the obvious choice for pro-life Republicans — a man with nothing to prove to opponents of legalized abortion.

The statement from Senator McCain of Arizona was a study in contrasts. The phrase “laying it on thick” springs to mind.

Said the senator, going on at some length: “Today’s Supreme Court ruling is a victory for those who cherish the sanctity of life and integrity of the judiciary. The ruling ensures that an unacceptable and unjustifiable practice will not be carried out on our innocent children. It also clearly speaks to the importance of nominating and confirming strict constructionist judges who interpret the law as it is written, and do not usurp the authority of Congress and state legislatures. As we move forward, it is critically important that our party continues to stand on the side of life.”

Mr. McCain’s record on abortion is far more consistent than Mr. Romney’s (he can boast a 0% rating from NARAL). Yet he feels the need to prove himself to a conservative base that distrusts him instinctively.

One of the ironies of the current Republican primary has long been that, on paper, Mr. McCain is a near-perfect conservative candidate: pro-life, anti-pork, defense hawk. But a series of transgressions — campaign-finance reform, voting against the Bush tax cuts, leading a compromise with the Democrats on judicial appointments — have left him with a need to defend his record on all fronts.

Meanwhile, a socially liberal Republican, Mayor Giuliani, has been eating the Arizona senator’s breakfast, lunch, and dinner among conservatives.

Or at least he had been, until a number of high-profile stumbles on abortion began to drag his campaign down. First Mr. Giuliani said he supported taxpayer-funded abortion because abortion is a constitutional right. Then he said the Republican Party needed to “get beyond” abortion. While that statement was taken out of context by some outlets (he seems to have been saying only that the primary should be decided on issues other than abortion, such as economics and the war on terror), it still managed to enrage pro-lifers.

No wonder, then, that Mr. Giuliani’s statement yesterday sounded as if abortion was the absolute last topic his campaign wanted to address: “The Supreme Court reached the correct conclusion in upholding the congressional ban on partial birth abortion. I agree with it.”

Talk about terse.

Mr. Giuliani could have started clawing his way back with pro-lifers by demonstrating some enthusiasm in his statement. Instead he said the absolute minimum required, sounding more like a defendant being cross-examined than a presidential candidate.

The former mayor’s frustration is understandable. The Republican Party plays a cynical game with abortion. While its leaders rail against Roe v. Wade, it’s widely understood that if the hated court decision were overturned, it would represent a disaster for the party — robbing it of a crucial fund-raising and turnout-generating issue. So Republican politicians and conservative judges tinker around the edges of Roe, as with yesterday’s decision, but mostly they preserve the status quo.

In that respect, Mr. Giuliani’s impact on abortion would be no different than that of Mr. McCain, Mr. McCain’s no different than that of Mr. Romney, and Mr. Romney’s no different than that of President Bush.

And yet the charade rages on.