The House ethics committee will accuse Rep. Maxine Waters of breaking the chamber's rules after a year-long investigation into allegations she sought the Treasury Department's help for a bank in which her husband was invested, the committee said Monday.

The announcement was made less than a week after the committee announced 13 ethics charges against Rep. Charles B. Rangel, and threatens to dog Democrats in the run-up to November's elections. With two senior black lawmakers facing charges, it has raised questions about whether black House members are being targeted by ethics officials.

Ms. Waters, a California Democrat in her 10th term in Congress, challenged the finding, saying she did not benefit from her advocacy. She said she's opted for a public hearing to try to clear her name...