Fein asks why Ms. Pelosi is using her authority to sit on impeaching President Bush and Vice President Cheney. Perhaps the simplest explanation is an anticipation of a Democratic president who will reap the powers now being gathered by Bush. A Democratic president with powers like Bush ought to cause Republican nightmares.

There is another reason. In other cases where there was an impeachment proceeding, there was a civilized vice president to take over. In this case it would have to be both of them or nothing. If that were to happen Pelosi would become president. So any support from her for this would appear to be a naked power grab to almost everyone.

Unless I am wrong, isn't the Speaker of the House third in line for the presidency?

Yes, Pelosi is 3rd in line. As you note, there are serious political repercussions for the House Speaker, and by extension the Democrats, for any impeachment move. The Democrats actually have more to gain by letting Bush complete his term, assuming that the war in Iraq remains a mess in November 2008 and perhaps helped by a recession or some other crisis. Above this however is, as I noted before, is the precedent set with the increase of authoritarian powers by the executive branch (and allowed by Congress). Any sane Republican, conservative or not, would not want a Democratic president with the executive powers that Bush now has.