The ethical woes facing Democrats are piling up, with barely a day passing in recent weeks without headlines from Washington to New York and beyond filled with word of scandal or allegations of wrongdoing.

The troubles of Gov. David A. Paterson of New York, followed by those of two of the state’s congressmen, Charles B. Rangel and Eric J. Massa, have added to the ranks of episodes involving prominent Democrats like Eliot Spitzer, Rod R. Blagojevich and John Edwards.

Taken together, the cases have opened the party to the same lines of criticism that Democrats, led by Representatives Nancy Pelosi, now the House speaker, and Rahm Emanuel, now White House chief of staff, used effectively against Republicans in winning control of the House and Senate four years ago.

The mix of power and the temptations of corruption can be a compelling political narrative at any time. But with voters appearing to be in an angry mood and many already inclined to view all things Washington with mistrust, the risks for Democrats could be that much greater this year.