It’s harder to be a moderate in Washington, D.C., than ever before. Nobody knows that better than the veteran centrist Democrat Henry Cuellar, who faces prosecution from the federal government for his work on one of the few remaining bipartisan causes in Texas politics: the glorious nation of Azerbaijan. On Friday, the Department of Justice indicted Congressman Cuellar, who represents Laredo, on fourteen counts, including bribery, conspiracy, failure to register as a foreign agent, and money laundering. Cuellar and his wife, Imelda, are alleged to have used a network of shell companies to hide $600,000 in payoffs from a Mexican bank and an Azerbaijani oil company. For those payments, the feds allege, Cuellar offered concrete deliverables, the “quid” for the “quo.” Cuellar is supposed to have…