Rush Limbaugh said today he was "sincere" and "heartfelt" in his apology to Sandra Fluke, as he explained that he never believed the Georgetown University student was a "slut" or "prostitute" when he said those words last week.

The furor over Limbaugh's remarks continued as more companies dropped their advertising from the show.

Sears and Allstate issued statements Monday after their ads appeared on Limbaugh's syndicated program. Sears Holding Corp., which operates Sears and K mart, tweeted that it did not "intentionally" advertise on Limbaugh's program, and is taking steps to make sure its ads don't run on the show. Allstate said in a Facebook post its ads were "mistakenly" placed on the program.

"We have asked our media-buying firm to correct the error by discontinuing any advertising on the Rush Limbaugh Show moving forward in keeping with our original advertising plans and strategies," Allstate said in a Facebook post.

Limbaugh today addressed the outcry over his comments about Fluke and even joked about losing advertising.

"Those two words were inappropriate. They were uncalled for and they distracted from the point I was actually trying to make," Limbaugh said, before criticizing what he calls President Obama's "socialist agenda."

Fluke, a 30-year-old law student, said on ABC's The View today that Limbaugh's apology changes nothing.

"I don't think that a statement like this issued, saying that his choice of words was not the best, changes anything, and especially when that statement is issued when he's under significant pressure from his sponsors who have begun to pull their support," Fluke said in her interview.

Don Imus today called Limbaugh's apology "lame" and referred to his fellow radio talk show host as an "insincere pig" on his program, according to video sent out by Media Matters.

In 2007, Imus' program was canceled by CBS after he made racially insensitive remarks about the Rutgers University women's basketball team.

Limbaugh issued a statement Saturday apologizing to Fluke for making "insulting word choices" as he tried to be "humorous." The apology came after intense criticism from Republicans and Democrats. Obama telephoned Fluke on Friday and offered his support.

Under the Obama rule, most employers are required to offer health insurance that includes coverage for contraceptives without any co-payment. It was amended after intense criticism from Catholic groups so now religious institutions can avoid paying for birth control as long as their insurance providers do so.

Today, the pro-Gingrich super PAC Winning Our Future is still advertising on the Limbaugh show. Gingrich said yesterday on Sunday talk shows that he believes Limbaugh did the right thing by apologizing.

AOL, Tax Resolution Services, Pro Flowers, Quicken Loans, Sleep Train, Sleep Number, Citrix Systems Inc., Carbonite and Legal Zoom have all pulled their advertising from Limbaugh's show, according to the Associated Press.

GOP presidential candidate Ron Paul, appearing Sunday on CBS' Face the Nation, said he didn't believe Limbaugh was sincere in his apology. "I don't think he's very apologetic," the Texas congressman said. "He's doing it because some advertisers took their advertisements off his program. It's his bottom line that he was concerned about."

Clear Channel's Premiere Radio Networks has Limbaugh on contract through 2016. The AP says the company stands by Limbaugh.

"The contraception debate is one that sparks strong emotion and opinions on both sides of the issue," Premiere Networks said in a statement e-mailed to AP on Sunday. "We respect the right of Mr. Limbaugh, as well as the rights of those who disagree with him, to express those opinions."

(Contributing: Martha T. Moore; the Associated Press)