Rupert Murdoch's 78th year has been busy. With the exit of the Wall Street Journal's native managing editor, Marcus Brauchli, the Australian media mogul's lieutenant now has a free hand to turn the business newspaper into a broader national title. We're hearing this afternoon that Daily News owner Mort Zuckerman has dropped out of the bidding for Newsday, clearing the way for Murdoch's News Corporation to take control of a third newspaper in the New York market. And the New York Post is this week shrinking to allow the News Corporation tabloid to be produced on the same presses as the Journal. But here's the question: why the rush? There are three main reasons: newspaper publishing economics; the broader synergies available to a media group with heightened political influence; and mortality.

1. Publishing economics. The New York Post's new size, 12 inches high, down from 13½ inches, will make it the size of the Wall Street Journal, folded in two. I'm told this will allow both Murdoch-owned papers to be produced on the same presses. If Murdoch's rumored $580m bid for Long Island's Newsday goes through, News Corporation will achieve even greater savings. A person familiar with the deal said the deal, by combining printing and distribution of the New York Post with another title in the same metropolitan market, would wipe out the $50m in annual losses that the Australian media titan still bears on his beloved New York tabloid. This move would be straight out of News Corporation's UK playbook: there, the media conglomerate transformed the profitability of its UK titles in 1986 by breaking the print trade unions and moving production of The Times, The Sun and other London papers to a heavily fortified print works in Wapping.

2. Influence. Rupert Murdoch may be the personification of the press baron, but he's never had anything like the influence in the US that his array of newspapers and television networks brought in the UK. His solitary US newspaper title, the New York Post, has given Murdoch influence over New York City and State politics, but precious little juice in Washington, DC. Murdoch has never had the access to the White House, even under George Bush, that he had to Number 10 Downing Street during Tony Blair's tenure as UK prime minister. Fox News is powerful, of course, but the cable news network is too reflexively conservative to provide any real influence over the liberals who are likely to run national politics, and appoint regulators, over the next political cycle. By creating a national title in the Wall Street Journal, and taking control of about half the New York newspaper market, Murdoch or his successor should be able to withstand any political effort to break up his empire. Look at the UK: the Labour party, which long sought to curtail News Corporation's media power, has entirely given up; about a decade ago, Murdoch passed the critical threshold beyond which he became untouchable. By creating a similarly interlocking network of television and newspaper operations in the US, he can achieve a similar result on a grander scale-if competition authorities allow.

3. Mortality. Last month, the Australian media mogul turned 77 years old. His motives are hard to divine, but one has to presume that the nightmare would be the breakup of an empire he has spent a lifetime in building, the fate which awaits Time Warner and Sumner Redstone's holdings. News Corporation is the one media conglomerate which makes some sense: the profits are made on sports and entertainment broadcasting; tabloids and quality newspapers provide political protection. That's the formula in the UK, at least. In the US, the richest media market, Murdoch bought New York Post in 1976 and has gradually accumulated television stations over the three decades since, launched a fourth entertainment network and a surprisingly successful cable news channel, Fox News. But it is only now, as proprietors such as the Bancroft family and Sam Zell lose hope in the future of newspaper publishing, that Murdoch has been given the scope in the US to achieve the same concentration he has in the UK. And it is no wonder that Murdoch is in such a rush. These newly available newspapers need a dramatic intervention if they are to make the transition to the internet. Potentially hostile Democrats are about to take control of executive and legislative branches of government. And Murdoch, the last great media mogul, is mortal. The aging press magnate can deny the reality by wearing black polo-neck sweaters on the urging of his much younger wife, but he doesn't have much time to conclude his legacy.

(Citizen Kane's desolate mansion, in the Orson Welles movie based loosely on the life of William Randolph Hearst, the pre-eminent press baron of an earlier age.)