(Andrew Burton/GETTY IMAGES)

“On June 6, 2011, Representative Anthony Weiner disclosed conduct which he described as inappropriate,” Pelosi wrote in the letter, which she sent Tuesday to Ethics Committee Chairman Jo Bonner (R-Ala.) and Rep. Linda Sanchez (Calif.). “An investigation by the Ethics Committee to determine whether the Rules of the House of Representatives have been violated is warranted.”

Weiner said in a statement Monday that he would “welcome and will fully cooperate” with an investigation by the committee.

National Republicans seized on the scandal Tuesday as Republican National Committee Chairman Reince Priebus called on Weiner to resign. House Republicans’ campaign arm pressured Democrats to return contributions they have received from Weiner. Already one Democrat, Rep. Betty Sutton (Ohio), has said she will donate to local charities the $1,000 that she received from Weiner’s campaign committee last year.

Aside from Pelosi and Democratic Congressional Campaign Committee Chairman Steve Israel (N.Y.), however, most top Democrats have declined to discuss the scandal.

“I know Congressman Weiner,” Senate Majority Leader Harry Reid (D-Nev.) told reporters Tuesday after the Democrats’ weekly policy luncheon. “I wish there was some way I can defend him, but I can’t.”

A few moments later, another reporter asked Reid what advice he would give to Weiner if the embattled Democrat requested it?

“Call somebody else,” Reid replied.