Forgive John Kerry if he doesn’t see any humor or humility in Bill Clinton’s “because I could” line. From Kerry’s unhappy perspective, Clinton’s flip explanation of his dalliance with Monica Lewinsky could also explain the lousy timing of Clinton’s book.

At least Monica got a kiss. Poor Kerry gets the kissoff.

Welcome to the All-Bubba, All-The-Time summer. Before the spectacle runs its course, the junior senator from Massachusetts could well be the Incredible Shrinking Candidate.

Week One illustrated the problem. Kerry’s open-secret search for a running mate should have been the hot campaign story, but Clinton hogged all the political air with just the runup to today’s official publication of “My Life.”

Teasing excerpts from his interview with Dan Rather, which filled the entire “60 Minutes” program Sunday night, relegated Kerry to also-ran status in face-time.

Even Rather’s talking to other reporters about the book — “Five stars!” Dan declared — got more attention than anything Kerry did. All that was before Monday’s intimate book party for 1,000 people at the Metropolitan Museum of Art.

Then there was Clinton at the screening of “The Hunting of the President.” Produced by friend Harry Thomason, the movie’s Clinton-as-victim theme dovetails perfectly with the ex-president’s own view of the Kenneth Starr wars.

No doubt it’s a coincidence the book and movie are being released at the same time.

Never mind that pesky presidential campaign or the Democratic nominee’s trouble getting traction against a wounded president. A week after he shut down to watch George Bush lead the national mourning of Ronald Reagan, Kerry was elbowed aside again. He even had to endure the Clinton/Bush lovefest when Clinton’s White House portrait was unveiled.

Kerry will just have to wait some more now as history is rewritten and redebated. He must stand by helplessly because Clinton’s famously insatiable appetites, especially for the limelight, must be served.

So while Clinton was saying that being impeached was a “badge of honor” and curiously claiming that conservatives turned to attacking him as a substitute “after the Berlin Wall fell,” Kerry was preparing to jet off to Nantucket for a low-key weekend in the sun.

He could have gone to Coney Island and no one would have noticed.

Kerry, of course, is charisma-challenged by a mannequin, but Clinton provides an especially unflattering contrast. One fact stands out: The ex-president, at 57, is three years younger than the man who wants his old job.

And Clinton still stirs stronger passions among the party base, where there is nostalgia for that innocent time in ’98 when the stain on an intern’s dress almost made Al Gore president.

Who would have thought then that Hillary Clinton would be a senator and Bill would be adding to his multimillions with blockbuster book sales? Why, he’ll soon be as rich as Marc Rich.

But the damage to Kerry isn’t just stylistic. Take Vietnam. A bedrock of the Kerry campaign is that he was winning combat medals while Bush was goofing off in the Texas Air National Guard.

But Clinton clearly evaded military service, making Bush look good by comparison — and helping to make the issue moot.

Take Iraq. Kerry’s efforts to attract the anti-war vote have been difficult enough because he supported the resolution authorizing force.

Now along comes Clinton telling Rather he basically supports the war.

There is, naturally, a Clinton spin to this center-stage grab: Bill’s book tour, an aide insists, is all being coordinated with Kerry’s campaign.

File that one next to “I did not have sexual relations with that woman.”

Michael Goodwin is a Pulitzer Prize-winning columnist for the New York Daily News. His e-mail address is Mgoodwin@edit.nydailynews.com.