By the time polls closed Tuesday in Wisconsin, Rick Santorum was already in his home state of Pennsylvania, where he is scheduled for three campaign appearances today in Carnegie, Hollidaysburg, and Mechanicsburg. Meanwhile, the media were gearing up to promote the “inevitability” of Mitt Romney, who was predictably the winner of primaries in Wisconsin, Maryland, and the District of Columbia. Santorum wasn’t even on the ballot in D.C. and had not campaigned in Maryland, instead devoting the past 10 days — following his March 24 Louisiana victory — to an all-out push in Wisconsin.

The outcome of Tuesday’s primary in the Badger State was in some sense predictable, a repeat of the primaries Feb. 28 in Michigan and March 6 in Ohio: Santorum campaigned hard and came close, but was ultimately unable to overcome the Romney campaign’s vast advantages. In the past 10 days, the former Massachusetts governor rolled out endorsements from Wisconsin Sen. Ron Johnson and Rep. Paul Ryan, as well as former President George H.W. Bush and Florida Sen. Marco Rubio, a Tea Party favorite who is almost every Republican’s top pick for the vice-presidential nomination. And once more — as in Michigan, Ohio, and other key states — Romney’s campaign and his allied “super PAC,” Restore Our Future, unleashed an overwhelming flood of attack ads against Santorum. It is estimated that the pro-Romney forces spent more than $3 million on advertising in Wisconsin, outspending Santorum and his super PAC by 4-to-1.

This was predictable, based on previous precedents, as was the final result Tuesday: In a Republican primary with phenomenally low turnout, Romney won Wisconsin with 42 percent of the vote to 38 percent for Santorum. This four-point margin of victory, purchased at such a heavy price, was predictably hailed as a triumph that effectively clinched the nomination for Romney. Yet the winner of Tuesday’s Wisconsin primary got about 200,000 fewer votes than the half-million Republicans who voted for Johnson in the state’s 2010 Senate primary, the low turnout in this year’s presidential primary an ominous indication of the tepid enthusiasm for Romney among grassroots conservatives. (Newt Gingrich did not even campaign in Wisconsin, but his 6 percent of the vote there was larger than Romney’s margin of victory.) If Romney is indeed now the “inevitable” nominee, it is a status he has obtained by crushing conservative opposition in an astonishingly expensive and negative campaign: According to the Washington Post, Romney’s super PAC has spent nearly $30 million on advertising, 91 percent of it on negative ads aimed at either Gingrich or Santorum. By some estimates, the Romney campaign is spending at a rate of more than $15 per vote, compared to less than $6 per vote for Santorum.

None of that was mentioned Tuesday night in the post-primary discussion on Fox News, which predictably cut off Rick Santorum’s speech halfway through, and then predictably began discussing the campaign in terms of when Santorum would drop out and how Republicans could “coalesce” behind Romney who, the commentators declared, is now definitely the inevitable nominee. Karl Rove, Charles Krauthammer, Mary Katharine Ham, Stephen Hayes — every voice on Fox News was singing the same predictable tune from the hymnal of inevitability. Santorum’s supporters have been complaining for weeks about the transparent pro-Romney bias at Fox, and it was perhaps not entirely a coincidence that conservative columnist Michelle Malkin — a Fox News contributor who endorsed Santorum in January — chose Tuesday to link election coverage from MSNBC and CBS at her popular blog. The bandwagon psychology of the front-runner’s argument, which has been gathering force ever since Romney’s Jan. 31 victory in Florida, has nearly overwhelmed all rational resistance. Anyone who continues arguing against Romney’s inevitability is increasingly viewed as a spoilsport, if not indeed a madman.

A sort of cognitive dissonance is at work: Three months into the primary campaign, Romney has gotten about 41 percent of Republican votes so far. According to projections by the Associated Press, however, Romney now has 655 delegates, which is 57 percent of the “magic number” of 1,144 needed to clinch the nomination at Tampa. Delegate-rich states that are home to millions of conservative voters are still weeks away from their primaries, including Indiana and North Carolina on May 8 and Texas on May 29. Yet such is the pressure now to unite Republicans behind Mitt’s moderate banner that Tuesday night on Fox News, Krauthammer argued that Santorum should quit even before the April 24 primary in his home state of Pennsylvania.

That was perhaps predictable, too, because Krauthammer and the other Fox News panelists surely know that if Santorum can manage to win Pennsylvania and fight on into May, the inevitable Romney may not be as inevitable as some pundits have predicted. According to an analysis of Republican delegate math published Tuesday in the New Yorker, it is currently projected that Romney will complete the primary campaign just shy of the “magic number.” Unless Santorum can somehow be pushed out of the race soon, there remains the possibility that the fight for the GOP nomination will go all the way to the August convention in Tampa. And in his Tuesday night speech in a suburb of Pittsburgh, Santorum signaled that he doesn’t intend to quit now.

“Pennsylvania and half the country have yet to be heard,” he told his home-state supporters. “We’re here to make sure their voices will be heard in the next few months.”

Santorum spent months campaigning on a shoestring budget in Iowa when there were no big crowds and no major media coverage, when his poll numbers were in single digits and nobody thought he could win. He won not only Iowa, but also Missouri, Minnesota, Colorado, Tennessee, Oklahoma, North Dakota, Kansas, Mississippi, Alabama and Louisiana, to become the last man standing against Romney, who has always been the pre-emptive favorite to win the nomination. Anyone who thinks Santorum will quit now — when he has three weeks to win over Republican voters in his home state of Pennsylvania, and thus keep his underdog campaign alive — obviously doesn’t know Rick Santorum very well. The key message of his speech Tuesday was therefore predictable: “It’s time to go out there and fight.”