Tangled Role in G.O.P. War Over Tea Party Gabriella Demczuk/The New York Times Steven C. LaTourette, a former congressman, runs a group that supports centrist Republicans against Tea Party challengers. WASHINGTON - In the year since he stepped down from Congress, Steven C. LaTourette, a Republican from Ohio, has emerged as one of the top generals in the establishment Republicans" war against the Tea Party. It is a role that has benefited the Main Street Partnership, a corporate-backed advocacy group he runs, and its effort to raise millions of dollars to protect centrist Republicans from Tea Party challengers. It has also helped draw clients to a separate lobbying office Mr. LaTourette and his wife have set up across the street from the Capitol. But this blitz of activity has led to complaints from Mr. LaTourette's political opponents that under the guise of defending the Republican Party from extremists, he is profiting from his continued presence in the Washington spotlight. In addition, Mr. LaTourette's activities have raised questions about whether, in his dual roles, the former congressman violated the federal statute that prohibits lawmakers from lobbying on Capitol Hill for a year after leaving office. Mr. LaTourette's situation underscores a new reality as the fierce divisions in the Republican Party unleash tens of millions of dollars in corporate funds, campaign donations and advocacy efforts, creating potential windfalls for well-positioned strategists and former officeholders. It also illustrates how vague the rules are governing lobbying by former members of Congress. Mr. LaTourette, who stepped down after 18 years in the House, citing his frustration with the bitter partisanship on Capitol Hill, said that any suggestion that his role in championing centrist Republicans is driven by financial self-interest or violated the lobbying ban "is just nonsense." And he said any encounter he has had with lawmakers has not had the "intent to influence official action," which is specifically banned. His work for the Main Street Partnership, he said, is focused solely on helping lawmakers who believe in the government's ability to solve problems to fight back against extremist groups like the Club for Growth, which he has likened to a "cancer that has attached itself" to the Republican Party for its role in challenging incumbent Republicans with more conservative candidates. "We want our party back," Mr. LaTourette said in an interview. Mr. LaTourette's activities since his departure from Congress have involved at least four distinct legal entities that he now runs or helps run: the Main Street Partnership, the nonprofit group of which he is the president and chief executive, which raises money from corporations and lobbyists; the Main Street Advocacy fund and Defending Main Street SuperPAC, which together are seeking to amass $8 million to bolster Republican candidates facing Tea Party challengers in the 2014 races; and McDonald Hopkins Government Strategies, the lobbying office he set up, which pushes the agenda of clients as diverse as CSX, the freight railroad giant, and Citizens for Responsible Energy Solutions, a group that promotes renewable energy. It is his role as head of the Main Street Partnership, which he took over after leaving the House, that has elicited questions. The Main Street Partnership is an unusual enterprise for Washington. It models itself as a tax-exempt social welfare group that generates research on topics such as immigration laws, health care and the federal tax code. But it lists as its members 52 House Republicans and three Senate Republicans - all centrists - and its bills are paid by corporations, lobbyists and other donors, who each pay dues of up to $25,000 a year, raising about $1.4 million, according to the organization's chief operating officer. By bankrolling the group and contributing money to an affiliated political action committee that donates money to the lawmakers who are members, corporations gain the right to help draft the Main Street Partnership's position papers and to participate in events that feature sitting members of Congress. The list of corporate members is kept secret, but the companies that donate to the group's political action committee, including General Electric and Dow Chemical, as well as Mr. LaTourette's law firm, offer a hint. Under House ethics rules and federal criminal law, former lawmakers are prohibited for one year from communicating with members of Congress "with intent to influence official action on behalf of anyone else," even if they are doing so on behalf of a nonprofit group, like the Main Street Partnership. But Mr. LaTourette has participated over the past year in private events, sponsored by the Main Street Partnership, that have brought him into direct contact with sitting members of Congress, the group's own website shows.