Senator John McCain can’t get over the fact that, four years ago, he lost the presidency to a man he seems to despise. McCain is carrying the biggest grudge in Washington, and it seems to be coloring everything he says and does.

READ Did the John McCain We All Once Admired Ever Truly Exist?

by Alex Wong/Getty Images.

In December 1965, when A Charlie Brown Christmas premiered on CBS, John McCain was a newly married navy pilot stationed in Meridian, Mississippi, and his sub-specialty was Happy Hour, so I rather doubt he caught the show. But it occurred to me as I watched the program’s annual telecast with my children this week that McCain could benefit from its gentle, redemptive spirit.

Because McCain, once the roguish imp of Washington and the Senate—a man who told the truth and relished the telling—has become the grumpiest man in town, a Lionel Barrymore whose long-nursed resentment at losing the 2008 election to Barack Obama has found new energy in his campaign against the prospect of U.N. ambassador Susan Rice as secretary of state.

McCain’s animus seemingly knows no bounds. Last month, he lashed his onetime friend Colin Powell for endorsing Obama for a second time, saying, “You’ve harmed your legacy even further.” (The forum for that remark was Fox News Radio, naturally.) Despite his ceaseless demands for more information about security lapses at the American consulate in Benghazi, Libya, McCain actually skipped a closed-door briefing with top military and counterterrorism officials on the matter the other day, then bristled when a CNN producer dared to ask him about his absence. “I have the right as a senator to have no comment,” McCain said, “and who the hell are you to tell me I can or not?”

There are real questions about diplomatic security in Libya, but Rice had nothing to do with them from her perch at the U.N.

Graciousness has never been McCain’s long suit. He’s been a scrapper since his high-school days, when he was known as “McNasty,” among other things. But a certain classiness used to be the hallmark of his public personality. Now he just seems crass.

Moreover, in sheer practical and political terms, his relentless criticism of Rice for hewing to Sunday-talk-show talking points about the Benghazi tragedy being the result of a spontaneous demonstration that got out of hand, rather than a premeditated act of terrorism, seems off the mark. There are real questions about diplomatic security in Libya, but Rice had nothing to do with them from her perch at the U.N. The C.I.A. itself says it scrubbed mention of al-Qaeda from her remarks. Is McCain really just steamed that four years ago, as an Obama-campaign adviser, Rice said he espoused “reckless” policies and tended to shoot first and ask questions later?

Whatever Rice said this week in a private meeting with McCain and Senators Lindsey Graham and Kelly Ayotte that was intended to calm the waters only seems to have turned up the heat.

But McCain should take a page from one of the great political grudge-holders of the 20th century: the Silver Fox herself, Barbara Bush. Tart as ever at 87, and even more unplugged with no dog in the fight, the former First Lady dispensed some unshrinking advice at the L.B.J. Library in Austin not long ago—at the very moment news was breaking of Mitt Romney’s contention that the Obama campaign had bought the election with “gifts” to various constituency groups.

“I’m tired now of the elections,” Mrs. Bush said in that wonderful Wasp way. “People spoke. Move on. Get on with it. I want to do other things and not be ugly.”

I’m old enough to remember when John McCain might have said something like that. I’m moved enough by the spirit of the season to hope he might yet.