These are heady days for Republicans. Their party controls everything in sight --- the Presidency, both houses of Congress, most statehouses --- and is poised over the next few years to tighten its ideological grip on the Supreme Court.

So what is Christine Todd Whitman doing playing Cassandra --- writing a book warning that all this could change in a hurry if, as she fears may happen, the party swings too far to the political right?

Whitman represents the tiny surviving band of top-level Republicans, most of them easterners like herself, who consider themselves moderates. She points out that George W. Bush won re-election last year by the smallest margin of any incumbent President in our history. From that fact comes her conclusion: the party must welcome voters from its moderate wing or it could very easily be tossed out of office within a decade.

In practical terms, Whitman says, this means laying off divisive issues like condemnation of stem cell research and opposition to abortion and gay marriage to concentrate instead on what she considers the party's central agenda: smaller government, fiscal responsibility and strong security. In place of the old political image of a party as a "big tent," she presents a down-home alternative --- the GOP as an umbrella, in which all Republicans subscribe to those central issues (the central umbrella shaft) while not abandoning their diverse interests in other more peripheral matters (the radiating umbrella ribs).

Her argument involves her in a delicate linguistic dance. She tries very hard indeed not to name names, especially that of President Bush. The hard-right activists who she sees as a danger to the party are nearly always "the administration," the "social fundamentalists," or even "the leadership." For example, while deploring the President's abandonment of opposition to a cap on carbon dioxide emissions, she treats him gently while laying the blame on "the anti-regulation element of the far-right base."

She devotes a long chapter to her service with the EPA and offers a defense of Bush's environmental record, which she claims has been grossly misrepresented. Her slant here is that the debate has been poisoned by extremist rhetoric and willful misrepresentation by both sides. She makes the same claim about the abortion controversy.

Her argument that inclusion of moderates is essential to the GOP's survival is, however, largely offset by a fact that she fails to mention: Since President Bush's re-election margin was so tiny, can't the hard-right "social fundamentalist" Republicans who she so deplores make exactly the same argument in their own behalf? Which is more essential to the functioning of that umbrella: the central shaft or the radiating ribs?

Whitman delves deeply into the history of the ideological split within the Republican party, dating its origin from the Goldwater campaign of 1964. She pleads with her party to be more open to blacks and women and less prone to drag religious issues into its campaigns. She calls for the nomination of a moderate Republican candidate for President in 2008, but she seems resigned to the fact that the hard-right conservatives, bolstered by gains in last year's election, are still running the show. Indeed, half of the gain in House seats registered by the Republicans in 2004 was due to the disputed redistricting of House seats in Texas dreamed up and masterminded by that hardest of hard-liners, Tom DeLay.

Christine Todd Whitman is in a difficult position in her party right now. She probably will be more comfortable promoting her views as a private citizen than she was as a member of an administration that permitted no dissent. The current Speaker of the House has publicly stated that he will not push for any bills that require substantial support from Democrats for passage. She might want to buy the speaker an umbrella.