David wu | David Wu won't resign

David wu - Wu did not issue a formal statement or appear in public on Sunday. A senior Democratic official confirmed for The Oregonian that Wu had made the decision.

"I call on the Ethics Committee to initiate an investigation into the allegations against Congressman Wu," she said in a statement.

"New allegations of unacceptable behavior by Congressman Wu are extremely serious and disturbing.

Wu, 56, has refused to answer questions about the incident.

Wu's announcement may also influence opinion in his district. Party member David Robinson of Aloha is pressing the effort.

Robinson, a commander in the Navy Reserves, ran against Wu in the 2010 Democratic primary, losing with 19 percent of the vote. He first considered pushing the no-confidence vote this winter, after reports first surfaced regarding Wu's troubled 2010 reelection campaign.

Announced challengers to Wu in next year's Democratic primary reacted swiftly Sunday night.

"David Wu's reported plan to remain in office but not seek re-election puts David Wu first and his constituents last," Oregon Labor Commissioner Brad Avakian said in a prepared statement sent to reporters.

State Rep. Brad Witt, D-Clatskanie, said Wu's announcement prompts new concerns.