Another election cycle, another threat to PBS funding.

This time, the attack comes from Republican presidential candidate Mitt Romney, who has called for an end to federal funding for the public broadcasting service. To make up for the shortfall, he wants PBS to begin running ads in its programs.

What does PBS President and CEO Paula Kerger think? "I'm glad that he said that he likes public broadcasting."

Kerger says PBS understands that these are hard economic times and tough decisions have to be made. But PBS, she says, has always had bipartisan support in large part because it is an "effective public/private partnership." "I think that what we hope to do is to make it clear that we have broad support from the American public."

It's also, she says, cost-effective support. PBS only gets, in aggregate, 15 percent of its budget from the federal government -- but it's a percentage that is vital to smaller, poorer, mostly rural stations. "That money can not be made up. We try to leverage it very carefully."

As for Romney's suggestion that the service run ads, Kerger points out that PBS couldn't do that even if it wanted to -- it would violate FCC regulations. But even more, she says, changing PBS to an ad-supported network would inevitably change what it airs because the network would be forced to show programs that attract advertiser-friendly crowds.

PBS, for example, continues to air ballet and modern dance, even though their ratings droop, because the service believes its important to present those arts to the viewing public. No ad-supported cable network would make a similar choice.

" There are a number of channels in the cable world that started out with really great ideas that they would be the commercial version of public television, and they went down very different paths." For an example, she says, take History. "Programming like Pawn Stars and American Pickers is not the same as American Experience and Ken Burns ... I'm not in the same business as anyone else who will stand on this stage."

Despite the threats, this has been a good year for PBS. Downton Abbey, which begins a much-anticipated second season on Sunday, was the third-most popular Masterpiece presentation since 1990 and walked away with a surprise Best Miniseries Emmy. Ratings are up for PBS Kids and up on Wednesday nights, thanks to Nova being moved there, which inspired the move of American Experience to Tuesdays as part of a "history night." And the service's attempts to expand its internet, mobile and social media presence, says Kerger, have started to bear fruit -- though she herself hasn't tweeted since November.

"I do use social media a lot, and I love reading other tweets ... I am determined that I will not stand up here in six months and be embarrassed again by my pathetic experiments in social media."

The public service is also continuing to make big plans, some inspired by the success of Downton. Kerger thinks the attention that show drew gives PBS an opportunity to reintroduce itself to the viewing public -- in the way, she says, pay cable stations use big hits to draw in new subscribers. "It's funny how many people have said to me 'PBS looks cool again.' I always thought PBS was cool."

Nor is the service taking the summer off. Coming this June, PBS will launch The PBS Summer Arts Festival 2012. Among the shows to be featured in the festival, which will be hosted by Anna Deavere Smith, are performances by The Kansas City Symphony, a documentary about Islamic art, and a film about John Leguizamo's one man show, John Leguizamo's Tales From a Ghetto Klown. "It's just one of the ways we're continuing to bring the arts home for millions of Americans," says Kerger.

Try to find that on commercial television.