NEW YORK - A quick schedule shift by the White House enabled President Bush to get considerably wider television exposure than he would have otherwise gotten for Thursday's prime-time news conference. Three of the nation's four biggest broadcasters gave the president a quick hook, however, by cutting away to entertainment programming before his session was finished. The White House moved the news conference from 8:30 p.m. EDT to 8 p.m. after realizing that CBS, Fox and likely NBC would not air it live. ABC said all along it would cover the president fully. The White House tried to be accommodating when it realized it had left the networks in a bind on the first night of the May "sweeps," when ratings are closely watched to set local advertising rates, said White House press secretary Scott McClellan. "I think this worked out for everyone involved," he said. Bush alluded to a tight television deadline before answering the night's final question. "I don't want to cut into some of these TV shows that are getting ready to air, for the sake of the economy," he said. He was already too late. Shortly before 9 p.m., both CBS and NBC shifted away from Bush for analysis as the next-to-last question of the news conference was being asked. The networks ignored the last two questions and were airing "Survivor" and "The Apprentice" before the president finished talking. Fox anchor Shepard Smith abruptly cut into Bush's answer of the final question to shift away to Paris Hilton and "The Simple Life: Interns." ABC stayed with the president until he concluded. Twenty-four hours earlier, the White House informed the networks that Bush wanted to set aside time for the fourth prime-time news conference of his presidency. Not only did the networks face a last-minute disruption during sweeps, it was to come on a Thursday - generally the most lucrative night for advertising revenue, largely because Hollywood studios are touting the weekend's new movies. It's especially important at top-rated CBS, where Thursday mainstays "CSI: Crime Scene Investigation," "Survivor" and "Without a Trace" are all regulars in Nielsen Media Research's top 10 shows of the week. NBC, facing a last-minute disruption to its popular game "The Apprentice," told the White House that it would be very hard for it to carry the news conference, spokeswoman Rebecca Marks said. Although it hadn't announced a decision publicly, the cable news network MSNBC advertised that its speech coverage would be anchored by Brian Williams, who would normally be on NBC. Both CBS and Fox announced by midday Thursday that they would stick with their normal prime-time schedules. ABC, which has a weak Thursday prime-time lineup, said it would cancel the movie "Sweet Home Alabama" for Bush. When the White House called at 4 p.m. to announce the time change, NBC said it would cover the event. CBS and Fox - not wanting to be left in the precarious public relations position of defying the president - quickly announced they would televise the news conference too. Although networks generally cover presidents' speeches and news conferences when requested, there is precedent for turning them down if there's no national emergency or if the request comes during a political campaign, said Martha Kumar, a political science professor at Towson University in Baltimore. "The networks are in a different kind of business than they were in the Nixon and Reagan years," Kumar said. "It is a business. News is less of a driver than entertainment." Bush's three previous prime-time news conferences occurred a month after the Sept. 11 terrorist attacks, during the days before the war in Iraq and 13 months after the war started, she said. CNN, Fox News Channel, MSNBC, CNBC and PBS all covered Bush, too. But even with those networks available in a majority of American homes, events like a presidential news conference get far greater exposure when they are on broadcast networks.