JUKEBOX JOHN PLAYS A NEW TUNE…. Sens. John Kerry, Lindsey Graham, and Joe Lieberman — a tri-partisan group — have been crafting a climate change bill that can generate broad support in the Senate. All three are personal friends with Sen. John McCain, and all three would love to get the Arizona Republican’s support on this issue that he’s historically cared about.

So, how’s that going?

“Their start has been horrendous,” McCain said Thursday. “Obviously, they’re going nowhere.”

McCain has emerged as a vocal opponent of the climate bill — a major reversal for the self-proclaimed maverick who once made defying his party on global warming a signature issue of his career.

Now the Arizona Republican is more likely to repeat GOP talking points on cap and trade than to help usher the bill through the thorny politics of the Senate.

McCain refers to the bill as “cap and tax,” calls the climate legislation that passed the House in June “a 1,400-page monstrosity” and dismisses a cap-and-trade proposal included in the White House budget as “a government slush fund.”

Former aides are mystified by what they see as a retreat on the issue, given McCain’s long history of leadership on climate legislation.

No one should be mystified. John McCain’s core beliefs don’t appear to exist.

McCain co-sponsored climate-change legislation three in three separate Congresses during the Bush era, and endorsed cap and trade as a sound policy. In 2008, however, McCain decided to oppose the same ideas he’d already endorsed, and he’s sticking with this far-right persona.

Asked for an explanation, McCain spokesperson Brooke Buchanan said, “This really hasn’t been done in a bipartisan fashion.”

I see. The climate bill is being pushed by a Dem (Kerry), a Republican (Graham), and an Independent (Lieberman), but the problem is that the effort is too partisan. Follow-up question for Brooke Buchanan: “Huh?”

Best of all, now that it looks like McCain will have to work even harder to impress the far-right GOP base, any hopes that he’ll step up and show some leadership on this all but disappear.

Some in the media think the president is to blame for not having “reached out” to McCain “enough.” As Atrios added, “Yes, obviously, it’s Obama’s fault that McCain’s flip-flopping on issues. In the Village, nothing is ever McCain’s fault.”

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.