Ogilvy Government Relations is rebuilding its Republican talent pool after having lost several of its top GOP lobbyists this year. The lobbying firm, which is owned by British advertising and public relations company WPP and regularly ranks among the top revenue generators on K Street, has hired House GOP Conference Chief of Staff Dee Buchanan and Con Lass, a lobbyist for the American Petroleum Institute. Lass, 42, was an aide to Republican Sen. Craig Thomas of Wyoming earlier in his career — Thomas died in office in 2007 — and was an aide to Sen. Alan K. Simpson, another Wyoming Republican, who retired in 1996. Buchanan was an aide to Texas Rep. Jeb Hensarling for more than 11 years. Hensarling has chaired the House Republican Conference— the No. 4 leadership job— since 2011 and is seeking the House Financial Services Committee’s top spot. Before working for Hensarling, Buchanan, 36, was an aide to Texas Republican Phil Gramm, who served in the Senate from 1985 to 2002.