Via Melissa McEwan, the New York Times gets a clue in an article titled, “On Signature Issues, McCain Has Shown Some Inconsistencies in the Senate.” Here’s the lede:

Senator John McCain likes to present himself as the candidate of the “Straight Talk Express” who does not pander to voters or change his positions with the political breeze. But the fine print of his record in the Senate indicates that he has been a lot less consistent on some of his signature issues than he has presented himself to be so far in his presidential campaign.

Mr. McCain, who derided his onetime Republican competitor Mitt Romney for his political mutability, has himself meandered over the years from position to position on some topics, particularly as he has tried to court the conservatives who have long distrusted him. His most striking turnaround has been on the Bush tax cuts, which he voted against twice but now wants to make permanent. Mr. McCain has also expressed varying positions on immigration, torture, abortion and Donald H. Rumsfeld, the former defense secretary.

The Times’ Elizabeth Bumiller goes on to identify McCain’s changing positions on the Bush tax cuts, abortion, immigration policy, Rumsfeld’s job performance, and McCain’s stance on torture (used to be against it, is now for it). Bumiller notes:

The risk, Republicans acknowledge, is that Mr. McCain may no longer be seen as above pandering and will be increasingly vulnerable to criticism from both sides.

John McCain is many things, but it should be crystal clear that he is not a maverick or a principled politician. He is a conservative Republican who will do and say whatever it takes to win the GOP nomination. The more the media wakes up to these facts, as Bumiller documented them, the more likely it will be that there will be a favorable atmosphere for the Democratic nominee to attack McCain and his record of unprincipled flip-flops.