WASHINGTON — House Democratic leaders began an orchestrated effort on Wednesday to force Representative Anthony D. Weiner of New York to resign his seat, saying his sexually explicit Internet messages and subsequent lies about them were making him, and the party, the subject of ridicule.

The push came as an angry Representative Nancy Pelosi, the minority leader from California, concluded that Mr. Weiner was becoming too much of a problem for his colleagues as they planned to retake the House in 2012.

The first — and most notable — call for Mr. Weiner’s resignation came on Wednesday afternoon from Representative Allyson Y. Schwartz, Democrat of Pennsylvania, a Pelosi ally who is overseeing the recruitment of the party’s candidates for the 2012 election cycle.

“Having the respect of your constituents is fundamental for a member of Congress,” she said in a statement released by her office. “In light of Anthony Weiner’s offensive behavior online, he should resign.”