* Latest apology couched as slap at "leftists"
* AOL is latest advertiser to flee from Limbaugh's show
* Birth control issue could hurt Republicans
WASHINGTON, March 5 (Reuters) - U.S. conservative broadcaster Rush Limbaugh said he had gone too far when he branded a birth-control activist a "slut," as he scrambled on Monday to defuse a controversy that has driven advertisers from his influential radio show.
In apologizing, the firebrand talk-show host couldn't resist taking a swipe at his opponents.
"I acted too much like the leftists who despise me. I descended to their level, using names and exaggerations," Limbaugh said. "It's what we've come to expect from them, but it's way beneath me."
Limbaugh's comments have amplified an election-year clash over President Barack Obama's plan to require health insurers to cover contraception.
Republican presidential candidates have cast the plan as an attack on religion as they court socially conservative voters before this week's 10-state "Super Tuesday" primary contest. But they have distanced themselves from Limbaugh's incendiary rhetoric as polls show that nearly two-thirds of voters support Obama's plan.
Limbaugh issued a written apology on Saturday for calling Georgetown University law student Sandra Fluke a "slut" and a "prostitute," after several advertisers said they would pull support from his show.
The broadcaster said his "choice of words was not the best."
He apologized again on Monday, but continued to criticize Fluke's efforts to force the Catholic university to include contraception in its health insurance coverage.
"If birth control insurance is important to you as an enrolling student ... you might want to attend or work at a school that isn't run by Catholics," Limbaugh said.
In a television appearance Fluke questioned whether the apology was sincere, adding that she did not want to hear from Limbaugh personally.
"The statements he's made about me over the air are personal enough, so I'd rather not have a personal phone call with him," Fluke said on ABC's "The View."
Limbaugh's apologies were also not enough for Internet provider AOL, which on Monday became the latest company to pull its advertising from the show.
"We have monitored the unfolding events and have determined that Mr. Limbaugh's comments are not in line with our values," AOL spokeswoman Caroline Campbell said.
Limbaugh said those companies were losing "the best opportunity they have ever had to advertise their wares."
Limbaugh's show is broadcast for three hours each weekday. Talkers Magazine, a broadcast industry trade publication, estimates that Limbaugh reaches at least 15 million people a week, the most of any U.S. radio talk show.
Monday's show included advertising from auto insurance provider Geico; Winning Our Future, a group allied with Republican presidential candidate Newt Gingrich; weight loss products; and a herbal "hormone balancing" product for menopausal women.
Limbaugh said he rejects "millions of dollars" in advertising each year for political reasons, including General Motors, which took a government bailout to avoid liquidation at the height of the 2008-2009 financial crisis.
Limbaugh's comments are the latest wrinkle in a battle over birth control and religious freedom that have emerged as a surprise hot-button issue in the 2012 presidential contest.
All four Republican presidential candidates have distanced themselves from Limbaugh's comments as they battle to take on Obama in the Nov. 6 presidential election.
Religious organizations, the Catholic Church and social conservatives have protested Obama's policy, which originally required all employers that provide health insurance to cover contraceptives, as an infringement on religious liberty.
Obama subsequently tweaked the policy so that religiously affiliated employers like hospitals, universities and charities would not be required to cover the cost. That did not satisfy Catholic bishops, who reject artificial contraceptives.
Republicans in Congress have unsuccessfully tried to repeal the new birth control rule, an effort that Democrats, in turn, have cast as a Republican "war on women."
The Democratic Congressional Campaign Committee says it has raised $1.6 million since Fluke testified on Capitol Hill two weeks ago, tying the flurry of donations to outrage over the Republicans' action.
Nearly two-thirds of Americans favor Obama's policy, according to a Kaiser Family Foundation poll released last week.
"It's a dramatic loser for the Republicans, because the vast majority of American women use birth control at some point in their lives," said Southern Methodist University political science professor Cal Jillson. (Reporting by Andy Sullivan; additional reporting by Yinka Adegoke)