Party animals: any chance Romney might govern as a moderate? For a clue, look at his senior staff.

• Author: Bernstein, Jonathan
• Position: TEN MILES SQUARE

What would a Mitt Romney presidency be like?

At one point over the summer, the candidate was offering, if elected, to "bury the hatchet" with Democrats, and his operatives are stressing how moderate and bipartisan Romney might be, even talking up how much they admire President Bill Clinton's governing style. That might seem plausible to some, since Romney has proven himself to be quite, shall we say, flexible on his policy positions.

But such a thought ignores some powerful fixed realities in Washington--realities that will push hard against whatever urges toward moderation Romney might harbor. The most obvious is the growing partisan divide in Congress, driven especially by the GOP's ideological turn to the right and the Tea Party's purging of Republican moderates, a trend that the 2012 election will almost certainly accelerate. Also, as I've pointed out in these pages ("Campaign Promises: What They Say Is How They'll Govern," January/ February 2012), presidents are under immense pressure from their strongest supporters to fulfill the specific policy promises they made to win the nomination, and Romney has taken positions so far to the right--for instance, not only endorsing Paul Ryan's budget plan but putting Ryan on the ticket--as to make compromise with the Democrats almost inconceivable.

But there's also a subtler, less noticed change in Washington that for years has been slowly undermining the capacity of administrations of both parties to compromise. Like any human organization, the White House is pro roundly influenced by the nature of the people who work there, especially in senior positions. And since the 1970s, the kind of people who surround presidents has changed. In the past, they were more likely to be people whose first loyalty was to the president himself, and only secondarily, if at all, to the president's party. In recent decades it's become just the opposite.

Consider an illustrative contrast: Karl Rove and H. R. "Bob" Haldeman. Both helped put a president into the Oval Office and then became powerful White House advisers. But Haldeman never worked for any other politician but Nixon, while Rove, long before he went to work for George W. Bush, was an all-purpose Republican operative, having advised, among others, Texas Governor William Clements, Utah Senator Bob Bennett, and Missouri Governor John Ashcroft.

What's happened over the last few decades is that the top people around the president have, like other players in...