The candidates, pundits and anchors are not the only ones fighting for screen time during the recent presidential debates.

Cable news networks are now frequently running commercials during special events in a large box alongside a smaller image of their coverage.

In the two hours leading up to the first presidential debate on Sept. 26, Fox News Channel showed commercials for big-name advertisers such as FedEx and General Motors on two-thirds of the screen while viewers were also able to keep an eye on the hubbub at Hofstra University before Hillary Clinton and Donald Trump faced off.

The networks’ thinking is that as long as there is program content on the screen, viewers will be less likely to switch channels.

Not every advertiser agrees to run in the dual screen breaks, which the television industry calls a “squeeze back.” But many are willing to try the format.

“Some of them feel strongly that they are paying for full screen and if that’s what they want, we make sure that’s what happens,” said Paul Rittenberg, executive vice president of national sales and marketing for Fox News Channel. “Others don’t care and accept the argument that ‘Hey, this is a win for you, because if we cut entirely to a commercial people are going to flip to another channel, because this thing is all over the place and this is a way to keep the viewer on the screen.’“

Fox News, CNN and MSNBC also used squeeze backs during the primary nights, when tabulated voting results could be shown in a box alongside commercials. Viewers can expect to see them on election night as well.

CNN declined to comment on its use of the format, but one executive who spoke on condition of anonymity said the minute-by-minute Nielsen ratings show that viewers switch away in droves during commercial breaks, so the network has to be willing to innovate.

Cable news started using squeeze backs during coverage of the 2012 presidential campaign season. But the format first evolved in sports TV around 2009, when ESPN introduced it during IndyCar race telecasts, which had no natural breaks for commercials. At the time ESPN called the format “side-by-side.”

“It was designed to keep you watching while the race was still going,” said Ed Erhardt, president of global sales and marketing for ESPN. “Most of the advertisers were comfortable, with a little cajoling.”