A top Washington, D.C., lobbying shop merged this week with a leading national bipartisan public affairs firm, bringing together former members of Congress and several well-known political operatives.

Mercury Public Affairs, which is based in New York but has offices in five other states and the District of Columbia, is merging immediately with Clark & Weinstock, a bipartisan lobbying firm with a substantial portfolio of energy industry clients. The new firm will be called Mercury/Clark & Weinstock in Washington and will operate under the Mercury brand in the cities where the public affairs firm already has offices.

Former Rep. Vin Weber (R-Minn.) is the managing partner of Clark & Weinstock, and top executives at Mercury include former Sen. Jim Talent (R-Mo.) and former Rep. Max Sandlin (D-Texas). Kieran Mahoney, a founder and partner at Mercury who has worked for an array of Republican politicians, including former New York Gov. George Pataki and former New York Sen. Al D'Amato, will become CEO of the joint operation.

"The combined bipartisan talent of Mercury/Clark & Weinstock strengthens our global leadership position in public strategy," Mahoney said in a statement. "Both firms have a reputation for superior talent, which delivers measurable business value for the world's most successful companies and advocacy groups."

In addition to the former members of Congress, Mercury's stable of ex-politicians includes former California Assembly Speaker Fabian Núñez (D) and former Bronx Borough President Fernando Ferrer, who was the Democratic nominee for mayor of New York in 2005.

Weber, in a statement, said his firm has worked successfully with Mercury before. Weber will become co-chairman of both Mercury and Mercury/Clark & Weinstock under the new arrangement.

"Mercury's public strategy platform, which includes a national grassroots mobilization network, leading state-based offerings in New York, California, New Jersey, Pennsylvania, Florida and Illinois, as well as capabilities in crisis communications, polling, digital, issue advertising and strategic communications, will create tremendous leverage for our capabilities in government relations," he said.

Mercury/Clark & Weinstock will be managed by a four-member operating committee reporting to Mercury President Kirill Goncharenko.

According to the company website, Clark & Weinstock's energy clients have included the Edison Electric Institute, General Electric Co., Great River Energy, the Large Public Power Council, Mid-American Energy Holdings Co., the Nuclear Energy Institute and Xcel Energy.