Rush Limbaugh should take lessons from Imus, liberal talk-show host Shultz Limbaugh apologized Saturday in an online statement for describing Sandra Fluke, the student who had spoken at a Democratic panel in support of insurance coverage for birth-control costs, as "a slut" and "a prostitute" on his radio program - criticism he intensified a day later by saying Fluke should post videos of her sexual activity online "so we can see what we're getting for our money." His statement Saturday - saying that his "choice of words was not the best" and that he was attempting to be humorous - amounted to a rare act of contrition for Limbaugh. But it only served to intensify the backlash against him, including from among his conservative allies. In the lead-up to Super Tuesday, the four Republican presidential candidates distanced themselves from Limbaugh's on-air remarks, with one, Rep. Ron Paul (Tex.) suggesting on "Face the Nation" on Sunday that Limbaugh's apology was prompted mainly by the loss of advertisers. Democratic National Committee Chairwoman Debbie Wasserman Schultz said she, too, doubted Limbaugh's sincerity. "I don't know any woman in America . . . that thinks being called a "slut" is funny," the Florida congresswoman said on "Meet the Press." At least seven national advertisers have pulled out of Limbaugh's show in the face of boycott movements that have sprung up on Facebook and Twitter. According to a tally by the Associated Press, the list includes mortgage lender Quicken Loans, mattress retailers Sleep Train and Sleep Number, software maker Citrix Systems, legal document services company Legal Zoom and the flower-delivery service ProFlowers. After initially issuing a noncommittal statement about its sponsorship of Limbaugh, Carbonite, a Boston company that sells data storage services, decided to pull the plug on Limbaugh on Saturday. "We hope that our action, along with the other advertisers who have already withdrawn their ads, will ultimately contribute to a more civilized public discourse," the company's chief executive, David Friend, said in a statement. In all, the controversy surrounding Limbaugh is beginning to look like the one that engulfed Imus. The one-time shock jock's radio career has never fully recovered after he referred to the Rutgers University women's basketball team as "nappy-headed hos" on his syndicated morning program in 2007. The comment ignited a firestorm of complaints and protests, which Imus initially dismissed. When advertisers scattered in the face of the public reaction, Imus offered a more sweeping apology but was subsequently fired by CBS Radio and MSNBC, which had also broadcast his program. Imus, of course, is no Limbaugh, a widely revered figure of the conservative movement and the most popular talk-radio host in the nation. Unlike Imus, whose program aired on a handful of stations at the time of his demise, Limbaugh's afternoon show is carried by some 600 stations across the United States and internationally, including WMAL (630 AM, 105.9 FM) in Washington. WMAL representatives were unavailable for comment on Sunday. He is so closely associated with the Republican establishment that Supreme Court Justice Clarence Thomas presided over his third wedding.