Keyes and Obama debate, October 21, 2004.   (Photo: Getty Images)

Obama: Alan Keyes
Obama fancies himself friends with everybody, but Alan Keyes, his feeble Republican opponent for Illinois senator in 2004, managed to earn Obama’s ire. After the original Republican nominee, Jack Ryan, was humiliated by the release of scandalous divorce records and dropped out of the race, Keyes was flown in from Maryland on the Carpetbagger Express to fill the void. With no chance of winning the election, Keyes was tasked with knocking the halo off Obama’s head, as one Republican state-senate colleague conceded. The plan, seemingly, was to attack Obama with the most outrageous allegations Keyes could devise: “Christ would not vote for Barack Obama,” he said. Obama condoned the “genocide” of black babies through his support for abortion rights. He wasn’t truly an African-American because he didn’t descend from slaves. He was a “hard-core, academic Marxist.” “I often had to suppress the rather uncharitable urge to either taunt him or wring his neck,” Obama writes in The Audacity of Hope. Instead, Obama effortlessly won the race.

McCain: Rush Limbaugh
Throughout his career McCain has made friends of Democrats and enemies of Republicans, but of the irate conservatives, Rush Limbaugh has been his most vocal and persistent opponent. In the 2000 presidential election, Limbaugh accused McCain of being intellectually dishonest and using tactics "right out of the Bill Clinton–George McGovern playbook." This primary season he has said that if McCain (or Mike Huckabee , as it happens) captured the nomination, he would “destroy the Republican Party.” ("I don't even listen to Rush," McCain has told Newsweek. "I'm not a masochist.") McCain has lately been trying to make nice with the Republican right wing, but he has not courted Limbaugh—and Limbaugh has not let up, recently saying "If you Republicans don't mind McCain's positions, then what is it about Hillary's positions you dislike? They're the same!"