Since clinching the nomination, John McCain hasn’t quite disappeared from the national stage. But little that he has said or will say could overpower the question that will dominate political journalism from now until June — and perhaps until August: Hillary or Obama? That question, and the daily jab-and-thrust on the Democratic side, will be the focus of every front-page story for months.

The McCain camp is largely fine with this. The country has endured marathon primaries that effectively began in January 2007. Most American voters aren’t political junkies. For them, summer will be about blockbuster movies, vacations, and baseball — not three months of relentless back-and-forth attacks. And little that is said by Hillary or Obama between now and the crowning of the Democratic nominee will be flattering to either of them.

As the all-but-official GOP nominee, McCain has done some of the traditional moves for a newly crowned champion — the international tour, the biographical tour, an appearance in the Senate to query Gen. David Petraeus. Another tour of non-traditional sites for Republican candidates is promised. All of these are fine efforts — but hardly earth-shaking or headline-grabbing.

So a major question for the campaign is: Can John McCain drive the news agenda? Every candidate is reactive to a certain extent: think George W. Bush having spring 2004 dominated by pictures of Abu Ghraib, or John Kerry trying to ignore the Swift Boat Veterans for Truth, or both candidates responding to a video featuring Osama bin Laden in the final days of the campaign. But unless the news cycle naturally spotlights a candidate’s preferred issues — which, given the U.S. media’s political leanings, is always easier for Democrats than Republicans — a candidate sometimes needs to make their own news and force the chattering classes to focus on their issues.

Last month, McCain offered a speech on the housing bubble, adamantly opposing a federal bailout, and offering the outlines of common-sense reforms. As sensible as McCain’s remarks were, the speech’s biggest news impact may have been in spurring Democratic ads claiming, in effect, that “John McCain offers no solution.” Let’s hope McCain’s speech in Pittsburgh today holds steady on this original theme. However the press would like to spin it, the fact is that McCain’s don’t-rob-the-responsible-to-bail-out-the-irresponsible theme will resonate with most Americans, if he can deliver that message to the country in the right circumstances, without creating opportunities for media distortion.

McCain aides note that the candidate’s preferred form of campaigning, town hall meetings with extended question-and-answer sessions, tend to be reactive and aren’t the perfect vehicle to set a message agenda. But there’s little chance of that format being dropped or modified. The candidate relishes them, usually wins over the majority of the crowd, and almost invariably gets glowing local press coverage.

And McCain’s people know that part of the price of that format is the inevitable off-key answer, such as the candidate’s impromptu parody of the Beach Boys, “bomb bomb bomb, bomb bomb Iran.” At the time, the crowd laughed; today liberal bloggers insist it is ipso facto evidence that he is Dr. Strangelove.

While many in the GOP laugh as the Democratic primary devolves into Judas Iscariot vs. Joe McCarthy, the current two-Democrats-vs.-one-Republican format does have its flaws for the nominee-in-waiting. A McCain gaffe will be one of two stories about the candidate on any given day; a Democratic gaffe could be one of ten stories about Obama or Clinton that day, along with the latest superdelegate endorsements, ad buys, poll and fundraising numbers, etc. When Democratic Senator Jay Rockefeller inanely charged that McCain didn’t seem to “care about the lives of people” because of his experience as a naval aviator, not a word of that silliness appeared in the next day’s Washington Post.

Thus, McCain faces the dilemma of having two rivals each significantly to the left of the mainstream — but only a limited amount of time and “ammunition” in each news cycle. Consider, for example, Obama’s frequent assurance to voters that, after withdrawing troops from Iraq, he would leave a “strike force” either in Iraq or somewhere else in the region to pursue al-Qaeda, if necessary. Details of Obama’s idea are, as usual, few and far between — and one has a hard time believing that this theoretical, vague group based somewhere in Kuwait, Bahrain, or Qatar would do a better job sniffing out al-Qaeda in places like Baghdad, Basra, and Ramadi than the troops now on the ground right there.

The media have given Obama a pass on his bizarre approach to al-Qaeda in Iraq, leaving it to McCain to deliver the much-deserved criticism. But it’s tough to play offense and defense simultaneously, and McCain’s team had to prioritize pushing back on the “100 years” attack over raising this question — at least for now. (The campaign’s e-communications director, Patrick Hynes, notes McCain did address the “strike force” question during his biographical tour last week, but for some reason, the reporters on the plane didn’t deem it newsworthy.) This is not to say that the issue will never be revisited; McCain campaign staff use the term “loaded and ready to go” on many of these issues.

McCain’s team believes the race is winnable and a remarkable sign of strength is that the candidate is running as much as 15 percentage points ahead of a generic Republican in polls. But they face two challenges. The first is making sure that the usual and inevitable bumps in the road inflict no lasting damage to their candidate; the second is making sure that their most likely opponent, Barack Obama, is finally held to the scrutiny he has so far largely avoided.

— Jim Geraghty writes the Campaign Spot blog on National Review Online.