(B) Mounting public worry about the prospect of a dual Clinton presidency. Maybe with Bill campaigning for Hillary — making the case for her, warming up audiences, disparaging the Democratic male contenders for piling on a lady — the public is beginning to confront the distinctly disturbing prospect of eight more years of Hillary and Bill and their same old tricks.

Combine all that with her shameless claims of centrism, and can there be any wonder at the wobbly wheels on her campaign wagon?

It doesn’t mean those wheels will come off. Hillary still leads nationally, she has extensive resources, and she has Bill (though an asset, he may be equally part of her problem). But she is beginning to look something less than inevitable.

Obama might prove as tough to beat — and never mind that the Clintons’ former political Yoda, Dick Morris, terms him “a Jimmy Carter, running for president on his personal moral outlook, his background and making a virtue out of his limited knowledge of how American government works.”

The Republican presidential field excels. Practically any of the leaders is a more commendable prospect than anyone in the Democratic dovecote. With Hillary, early Republican leader Rudy Giuliani may be fizzling, as well. At long last John McCain could be surging, paralleling the Petraeus “surge” in Iraq. As former Sen. Phil Gramm notes, “Republican primary voters know John McCain is the only great man running for president.”

Soon enough, we’ll know that, too.

Yet at this holiday season, the Democrats have given two marvelous gifts — not frankincense nor myrrh, but collapse in Congress and Hillary Clinton in what may be a fast fade. The two developments couldn’t have meshed at a more appropriate time.

The primaries are about to begin; we’ll know the nominees by mid-February. It’s a wonderful life: The gifts of Hillary and her fellow Democrats mean no one should rule out a Republican successor to George Bush just yet.