WASHINGTON -- As Republican calls for the resignation of Democratic New York Rep. Anthony Weiner mount, the party is being forced to confront its own uncomfortable reality: sitting Senator David Vitter of Louisiana.

Vitter was discovered to have regularly used the prostitution service of Deborah Jean Palfrey, also known as the D.C. Madam, after details of an investigation into Palfrey's service were leaked to Hustler magazine.

Vitter admitted to using the Washington, D.C.-based prostitution service in July 2007. Even so, 27 prominent Republicans gave a total of $161,700 to Vitter's 2010 reelection effort.

One of those Republicans was John Cornyn, the head of the National Republican Senatorial Committee. Cornyn called on Weiner to resign Wednesday. In 2009, he gave Vitter $10,000 and as chair of the NRSC directed another $42,800 to his campaign, according to Federal Election Commission records.

House Speaker John Boehner has yet to weigh in on Weiner, but if he does, he may have to answer questions about the $5,000 he gave to Vitter in 2010. Boehner was one of only three House Republicans to donate to Vitter's campaign.

In July 2007 Vitter admitted, first in a letter and then at a press conference, to have used Palfrey's prostitution service when he served in the House of Representatives from 1999 to 2004. Vitter was also revealed to have scheduled prostitution appointments during House roll call votes. Vitter had previously denied having an affair and paying for prostitutes, citing family problems for his withdrawal from a bid for the Louisiana governorship in 2002.

After the Palfrey revelations, a New Orleans-based prostitute, Wendy Yow, came forward and revealed that Vitter had regularly used her services after he was elected to the House in a special election to replace Rep. Bob Livingston, who retired to become a lobbyist after revealing his own affair.

Vitter continues to deny any involvement with Yow or other prostitution services aside from the D.C. Madam. Yow, however, passed a polygraph test administered by Hustler.

On Monday, Weiner admitted that he had sent a lewd picture to a follower of his Twitter account and then lied about it to the public and the media. He continued to explain that he had engaged in inappropriate online conversation with at least six women over the past few years. No money changed hands and no laws were broken.

Republican National Committee Chairman Reince Preibus has led the calls for Weiner to step down. On Wednesday he assailed the Democratic response to the scandal: "If Nancy Pelosi was serious about draining the swamp ... there are certain times that leaders need to step up and make a difficult decision to tell their own that they should leave."

On Tuesday, House Majority Leader Eric Cantor (R-Va.) stated, "I don't condone his activity. And I think he should resign." Cornyn echoed Cantor's call on Wednesday.

Other lawmakers who may be thinking twice before calling for Weiner's resignation include Bob Corker (R-Tenn.), Chuck Grassley (R-Iowa), John Barrasso (R-Wyo), John McCain (R-Ariz.), John Thune (R-S.D.), Jon Kyl (R-Ariz.), Lamar Alexander (R-Tenn.), Lindsey Graham (R-S.C.), Lisa Murkowski (R-Alaska), Mike Enzi (R-Wyo), Mike Johanns (R-Neb.), Orrin Hatch (R-Utah), Pat Roberts (R-Kan.), Richard Burr (R-N.C.), Richard Shelby (R-Ala.), Roger Wicker (R-Miss.), Saxby Chambliss (R-Ga.), Thad Cochran (R-Miss.), Tom Coburn (R-Okla.), Dave Camp (R-Mich.), Louie Gohmert (R-Texas). Each contributed to Vitter's reelection campaign.

Democratic leaders, including Minority Leader Nancy Pelosi (D-Calif.), have called for an ethics investigation into Weiner's social media use. House rules state that lawmakers "shall behave at all times in a manner that shall reflect creditably on the House." Others, including former Democratic National Committee Chairman Tim Kaine, Rep. Allyson Schwartz (D-Pa.), the top recruiter for the Democratic Congressional Campaign Committee, and Sen. Patrick Leahy (D-Vt.), have called on Weiner to step down.

An ethics complaint against Vitter was dismissed after the Senate Ethics Committee ruled that the alleged violations occurred prior to his tenure in the Senate and, thus, the committee did not have authority to investigate or punish the senator.

While Weiner has postponed an upcoming fundraiser with Matt Damon, Vitter continues to raise money. He held a Wednesday night fundraiser hosted by lobbyists.