Rupert Murdoch's Twenty-First Century Fox Inc. made an audacious offer for Time Warner Inc. that, if it succeeds, would transform the American media landscape and cement the 83-year-old's status as the most powerful magnate in U.S. media and entertainment.

While Time Warner, whose assets include the HBO cable channel and the Warner Bros. movie studio, rejected the $80 billion bid, Murdoch is unlikely to abandon the pursuit and has the "disciplined determination" to get the deal done, people close to the situation said. Investors expect he will eventually raise the offer and increase the cash component — 40 percent — to win the prize.

Murdoch's proposal, fresh on the heels of his high-profile divorce and a damaging phone-hacking scandal that involved his British tabloids, is aggressively bold even for a media mogul whose ambitions are legendary.