His advertisers are defecting. He’s facing increasing criticism from his own side. And the evidence is mounting that his continued tirades against Sandra Fluke are damaging the GOP. So Rush Limbaugh is attempting a last ditch, but tried-and-true strategy to stop the bleeding: Blame Barack Obama for creating the whole mess.

“Obama is sorely hurting with women in preelect polls,” Rush is now claiming. “He wanted to turn this into an issue much as they used to use abortion. So the Democrats played the game.”

Limbaugh’s latest theory: He alleges that Dems sprang a trap by pushing Sandra Fluke as a witness for the House hearing on contraception and religious liberty. “They wanted to turn this from a committee hearing on Obama and his unconstitutional mandate to the issue of contraception so as to bring back to life page 1-A of the Democrat playbook: Republicans Hate Women,” Rush says.

No one denies that Democrats see political advantage in this fight or that they think this debate should be about contraception. But it’s hard to see how this has all flowed from a secret plot hatched by Obama himself. The chronology is straightforward: After Obama took a beating over the original Obamacare rule requiring religious institutions to cover contraception — which Joe Biden himself conceded was a screw-up — Obama unveiled a new compromise exempting those institutions. This compromise was supported by some Catholic groups and — according to some polls — a majority of Catholic voters.

House Republicans held a hearing on February 16th on Obama’s new rule. Dems wanted Sandra Fluke to testify, but Republicans said Dems had submitted her name too late. Later in the week, Dems held their own hearing featuring Fluke. That is what triggered Rush’s original tirade. Beyond this, the battles over Planned Parenthood and the Komen foundation — which Republicans happily joined, and which laid the groundwork for the current contraception fight — predate Fluke’s entry into the fray.

At any rate, Rush’s latest effort to blame Obama for his whole mess doesn’t appear to be working. Since he made this case, five more advertisers have deserted his show, bringing the total to 20.

Meanwhile, a new Washington Times poll finds that a full 30 percent of Republican primary voters think this battle is about women’s health, and not about religious liberty. As pollster John Zogby puts it: “Drop this baby right now. Drop it. This is not a winner.”

Rush is discovering that not even blaming Obama can change this. It must be a pretty disorienting discovery.