ABC NEWS' Z. BYRON WOLF WRITES FROM THE ABC BOOTH IN THE U.S. SENATE:
The second measure in weeks to pit Sen. John McCain, R-Ariz., against two of his strongest supporters is coming down the pipeline.
Sen. John Warner was among the first to back McCain's quest for the presidency. Warner endorsed his Senate Armed Services Committee colleague back in February of 2007, even as the two were publicly airing very different thoughts about the troop surge.
But if Warner was one of McCain's first supporters, his actions recently have put McCain in some difficult situations. And he's getting help from Indy Joe Lieberman of Connecticut, another staunch McCain supporter.
After all, it was the backing by Warner and Sen. Chuck Hagel, R-Neb., and their public campaign in favor of a major overhaul of the GI Bill -- an effort to basically send all post-9/11 vets to college -- that really gave the bill some steam. Senators passed it last week with 75 votes. Lieberman was not one of the 58 cosponsors of the bill, but he did vote for it.
McCain, along with the White House and the Pentagon, thinks that GI bill will hurt military retention and, while he voiced his opposition to it, skipped the vote to campaign in California.
Next up is another tricky political maneuver for McCain. Climate Change.
McCain has been a leader in the Republican party in voicing concern about climate change and vocal in recent years in his support along with Lieberman for measures to create nation-wide greenhouse gas standards and let businesses that cannot meet limits trade for carbon credits with businesses that can.
But it is not McCain's name next to Lieberman's on the Climate Security Act Senators are set to debate next week. It's Warner's.
And McCain, although he and his Democratic rivals for the Presidency will all three miss the debate, is for the moment withholding support for the bill despite his past endorsement of a cap and trade system. He wants to make sure it contains more incentives for the development of nuclear energy. The rub, of course, is that those sorts of incentives would scuttle the bill for many Democrats.
So, When the Senate takes up the Climate Security Act, it will be the second measure in a row to take something McCain has built his career supporting - veterans two weeks and cap and trade legislation next week - and present it in a way that he finds unpalatable.
-- Z. Byron Wolf