Fox News, the top-rated cable channel, has announced its biggest shake-up of its daily lineup in several years — an overhaul that includes shifting one of its marquee news anchors, Martha MacCallum, out of her 7 p.m. spot to make way for an expansion of its prime-time opinion programming.

The move highlights the increasing dominance of conservative punditry at a network that positioned itself at its founding as a “fair and balanced” alternative to what it saw as a liberal drift in other media. Fox has not yet named a permanent host for the 7 p.m. slot and will instead feature “a rotating group of Fox News opinion hosts” in that hour after MacCallum moves to a lower-profile 3 p.m. slot next week. Brian Kilmeade, who co-hosts the “Fox and Friends” morning show, will be up first on Monday.

Rival news network CNN also unveiled a slate of programming changes that includes an expansion of news anchor Jake Tapper’s show and a shrinking of veteran anchor Wolf Blitzer’s.

Compared with shows with the Fox opinion hosts who follow hers in the evening — Tucker Carlson, Sean Hannity and Laura Ingraham — MacCallum’s show has significantly lagged in audience ratings. Notably, her show was defeated in the 25-to-54 age demographic — but not in total viewers — by upstart network Newsmax on one night in December, though the feat was not repeated. Her move means that Fox’s daily news programming will end after anchor Bret Baier’s 6 p.m. show concludes and not pick up again until anchor Shannon Bream’s show begins at 11 p.m.

MacCallum will take the afternoon time slot now held by news anchor Bill Hemmer. Hemmer will return to the morning show, “America’s Newsroom,” which he left to replace Shepard Smith, who abruptly resigned from the network in October 2019. But that morning show will now be two hours instead of three, beginning at 9 a.m., with co-host Dana Perino, the former White House press secretary, who previously hosted a 2 p.m. show.

Fox’s chief White House correspondent John Roberts will leave the beat to anchor a 1 to 3 p.m. news show with Sandra Smith, now the host of “America’s Newsroom”; his replacement at the White House has not yet been named. And Harris Faulkner, another key member of the network’s news division, is being moved from 1 p.m. to 11 a.m. She will remain a lead panelist on the 12 p.m. talk show “Outnumbered.”

Fox News CEO Suzanne Scott said in a statement that the new lineup “ensures Fox News Media will continue to deliver outstanding coverage for our viewers who depend on the most trusted names in the business.”

Fox News finished 2020 as the most-watched network in cable. But, in the wake of President Trump’s electoral loss to Joe Biden, CNN has been on a major upswing, while Fox’s ratings have experienced some softness.

In the last few months of 2020, CNN attracted more viewers than Fox News between 6 a.m. and 6 p.m. in the 25-to-54 demographic, though Fox was watched by more total viewers. In prime time, Fox News edged CNN by 15,000 prime-time viewers in the key demographic over the same time period.

CNN’s programming changes include an expansion of Tapper’s 4 p.m. weekday show from one hour to two, beginning in April, while Blitzer’s “Situation Room,” now a two-hour show that begins at 5 p.m., moves to a one-hour slot at 6 p.m. His show will air on CNN’s overseas networks, though. And CNN introduced a new delineation of the two anchors’ roles, describing Tapper as the lead for Washington news and Blitzer as a principal for breaking news.

Tapper will also take turns with chief political correspondent Dana Bash in hosting the Sunday morning “State of the Union” show. Abby Phillip will take over the Sunday edition of John King’s “Inside Politics” franchise, hosting from 8 to 9 a.m., beginning Jan. 24. And Pamela Brown will anchor a three-hour news block on Saturday and Sunday evenings.

CNN also announced that chief White House correspondent Jim Acosta, who rose to national attention as a sparring partner of Trump, will become an anchor and take on the new title of chief diplomatic correspondent. Kaitlan Collins will serve as the network’s chief White House correspondent for the Biden administration.