Fox News host Tucker Carlson. Fox News Fox News host Tucker Carlson will be promoted to the 9 p.m. time slot to replace outgoing host Megyn Kelly, the network announced Thursday. In addition, morning host Martha MacCallum will anchor the 7 p.m. hour for President-elect Donald Trump's first 100 days in office.

"In less than two months, Tucker has taken cable news by storm with his spirited interviews and consistently strong performance," said Rupert Murdoch, the executive chairman of Fox News and 21st Century Fox.

Kelly announced Tuesday that after 12 years at Fox News she had chosen to depart for NBC News. The move sent shockwaves through the cable-news industry, immediately prompting observers to speculate as to who would replace her.

Initial speculation led observers to believe the network would tap MacCallum, Trish Regan, Shannon Bream, Sandra Smith, or Kimberly Guilfoyle for the job. Conventional wisdom indicated that Fox News executives would look to appoint a female host for the role to offset an otherwise all-male prime-time lineup.

But Fox News chose to buck its tradition of having a female host in its traditional prime-time lineup, as the Drudge Report first reported, instead choosing Carlson for the post. MacCallum will, however, be in what Fox considers early prime-time at the 7 p.m. hour.

Carlson was only recently given his own show, "Tucker Carlson Tonight," which airs weeknights at 7 p.m. But ratings have soared since he took over the hour from former host Greta Van Susteren.

His show's inaugural night was Fox News' most watched telecast of the year in the time slot, with 3.7 million viewers tuning in. In the show's first month, Carlson posted double-digit increases from the previous year in the key 25-54 demographic.

"Viewers have overwhelmingly responded to the show and we look forward to him being a part of Fox News' powerful prime-time line-up," Murdoch said.

The decision to tap Carlson for the role signaled that Fox News would continue in the mold of ousted chairman and CEO Roger Ailes and assemble a strong prime-time lineup of conservative personalities while Trump resides in the White House.

The move to place MacCallum at 7 p.m. for the first 100 days also hinted that she could eventually be the permanent host of the evening hour. MacCallum has anchored "America's Newsroom" alongside Bill Hemmer since 2010.

If MacCallum, who has worked at the network as a down-the-middle news anchor for more than a decade, were appointed to that role, it would ensure news-centric programming provides a lead-in to Fox News' opinion shows.

"Martha is a versatile and skilled anchor who has proven to be an essential component of our news programming," Murdoch said. "For the last 12 years, our viewers have trusted her reporting and we are pleased she will be part of our prime-time line-up for the first 100 days of the new presidency."

Also for the first 100 days, Bream will anchor "America's Newsroom" with Hemmer. Bream, who often filled in for Kelly, has served as Fox News' Supreme Court reporter and anchor of Sunday's "America's News Headquarters."

Both MacCallum and Bream will begin hosting in their new hours the week of inauguration. Host Bret Baier will anchor 6 p.m. to 8 p.m. until the transition is made.