It doesn’t matter if Mitt Romney wins the Iowa caucuses tonight. He is about to experience a severe political hemorrhage over his refusal to disclose his tax returns.

Full disclosure: I am supporting President Obama for re-election because I agree almost entirely with his policies and I disagree with every Republican candidate on the fundamental issues I care about most.

But I must say I have admired Mitt Romney for a long time — for his business and political careers and, especially, for being a good father. I met two of his sons on different occasions in the “Green Room” (holding hospitality room) at Fox News Channel, where I am a contributor. And I remember thinking, “Whatever I like or dislike about Mitt Romney’s politics, he must be a great man to inspire such love and loyalty by two sons.

I also have many Republican friends who are strong Romney supporters, and whom I greatly respect, such as Mark DeMoss, a conservative Republican media specialist who represents many Christian evangelical organizations and has become a good friend of mine.

I became increasingly critical of Mr. Romney’s presidential campaign when he flip-flopped on some core issues that meant a lot to me — such as opposing Newt Gingrich’s position that an illegal immigrant who has been in the country for 25 years, with a job, family and history of paying taxes and being a good citizen, should be forced to go back to his country of origin without a system for allowing him to earn his way into U.S. citizenship. George Bush, John McCain and most decent people I know support Gingrich’s position. Why wouldn’t Mitt Romney, a moderate conservative and great dad with a big enough heart to inspire such love and devotion from his children?

No reason, except pure pandering. Which doesn’t shock me; it just disappoints me.

So getting to the topic at hand, whatever happens tonight in the Iowa caucuses — by the way, I predict Rick Santorum will eke out a victory over Romney, with Ron Paul in a virtual dead heat with Romney (there, I didn’t wimp out and say “too close to call”) — I predict that Romney is about to head down in the polls, will be wounded and will keep bleeding to the point of hemorrhaging starting tomorrow morning.

The conventional wisdom already is predicting this because Newt Gingrich, Santorum, Ron Paul and, if they stay in the race, Rick Perry and Michele Bachmann will all start hammering on Romney as the front-runner for some of his “liberal” positions, such as on choice and “Romneycare.”

But I don’t think this normal phenomenon of bashing the front-runner is going to be the key factor that will put Romney in great political danger.

I think the key factor will be Romney’s refusal to release his tax returns, which will bring into critical mass Romney’s biggest candidate vulnerability: the idea that he lacks candor and authenticity.

There will be many voters who will see Romney’s refusal to release his tax returns as exactly what it is — he doesn’t want people to know how wealthy he is, or perhaps (certainly this will be the suspicion) he is embarrassed for people to know how small a percentage of his total income he pays taxes on.

If that isn’t bad enough, Mr. Romney will undoubtedly compound the problem by denying that this is the reason. Instead, he will talk about the right to privacy, etc. — and no one will believe him because everyone will know the real reason. Which is to say, he will be reinforcing his image of being the plastic man who can’t tell it straight (already reinforced by his recent failure to take personal responsibility for the super PAC ads attacking Newt Gingrich).

Finally, Romney’s insistence on not disclosing his tax returns will show that he lacks the political savvy to understand the fundamental rule of crisis management that he should know by now: If the truth is coming out someday anyway, “tell it all, tell it early, tell it yourself” — rather than delaying, delaying, delaying the inevitable.

Richard Nixon should have cemented the consequences of violating this fundamental rule during Watergate.

Mark my words: at some point, one month, two months, four months — if he is the nominee, for sure some time in October — Romney will be forced to disclose his tax returns. And then it will be a HUGE story, not because we all know what we already know — that he is a wealthy man who pays a relatively small percentage of his income in taxes. No. By resisting and resisting the disclosure that is inevitable, he will be making the disclosure even more newsworthy than it would ordinarily be.

Sorry, Mr. Romney — even as a Democrat and Obama supporter, I take no pleasure in the pain and humiliation you appear to be intent on putting yourself through. But unless you release your tax returns right away — say, tomorrow or next week — that will be virtually unavoidable.

And if you persist, you will doom your chances to defeat President Obama — that is, if you are the Republican nominee.

Stay tuned.

Lanny Davis, a Washington attorney, served as special counsel to President Clinton in 1996-98 and as a member of President Bush’s Privacy and Civil Liberties Oversight Board in 2006-07. He is the author of the forthcoming book “Crisis Tales: Five Rules for Coping With Scandal in Business, Politics and Life,” to be published by Simon and Schuster in early spring 2012.