Here’s one of those great political mysteries we’d like someone to unravel for us. In the current political era of “throw the bums out,” why does U.S. House Speaker Nancy Pelosi continue to side with someone as ethically compromised and politically shameless as House Ways and Means Chairman Charlie Rangel?

She certainly ought to worry, given we’re in an election year when Democrats are especially vulnerable — maybe not in Pelosi’s safe San Francisco congressional district, where she’s virtually guaranteed re-election no matter what she does. (So much for war protester Cindy Sheehan’s plan to abandon her place in nearby Crawford and unseat Pelosi in 2008. She only made good on half of her threat, for which many in McLennan County are nonetheless thankful.)

Last week, the House Ethics Committee admonished Rangel for taking corporate-sponsored trips to the Caribbean in violation of House ethics rules. He promptly took to the House floor to blast his critics, insisting that it was only common sense he not be held responsible for his actions. Ironically, the ethics panel is still weighing other allegations against Rangel — everything from failure to pay taxes on rental income from a villa in the Dominican Republic to mixing business and ego in soliciting $1 million for a school named after him from a firm that had some business before Congress.

Even The New York Times, which unearthed much of this scandal in its zealous investigative reporting a couple of years ago, calls for Rangel to go.

For her part, Pelosi remains tone-deaf to the cries of not only Republicans but a growing chorus of anxious Democrats, demanding she dump Rangel from his perch as chairman of the House Ways and Means Committee, particularly with Election Day fast approaching and more and more voters questioning congressional leadership during this wobbly, jobless recovery.

Incredibly, Pelosi refuses to budge on the matter, saying she won’t consider action against the beleaguered chairman till the full investigation on his scandals is delivered to her. So much for her promise of running an ethically pure House of Representatives. Considering what the ethics panel already has found — and the rapidity with which Rangel lambasted the panel — she ought to take action now, not later.

On ABC News on Sunday, Pelosi insisted Rangel’s alleged ethical transgressions haven’t jeopardized our country in any way. Considering the impotence of Democratic leadership the stormy past year or so, the speaker could be right. Then again, who knows how much damage this poster child for ethical misconduct could do to Democrats like our own U.S. Rep. Chet Edwards in November?