But those efforts looked doomed to fail after Cochran didn't win his June 3 primary. Because both he and McDaniel fell short of 50 percent of the vote, both men entered a runoff race to be held three weeks later.
That was supposed to favor the insurgent state lawmaker, who seemed to emerge with momentum and confidence that his activist base would turn out again on Tuesday while overall turnout decreased, as it usually does in runoff elections. Even some of Cochran's fiercest allies appeared to dial back their criticism of McDaniel in the race's closing weeks, mindful that any criticism against him could help the Democrats in a general election.
But in a brilliant strategic ploy, Cochran and his allies — notably, the Super PAC led by Henry Barbour — focused their efforts on turning out black voters instead of winning over activists. Those voters, swayed by Cochran's pledges to continue delivering federal money to the mostly poor, rural state appear to have changed the composition of the electorate enough to give Cochran the win, according to an assessment of the early vote tallies.
In Jackson's Hinds County, where two-thirds of the population is black, Cochran was winning 82 percent of the vote (with about half of precincts reporting). In the primary, he only tallied 66 percent of the vote. Turnout was up significantly in heavily African-American counties in the Mississippi Delta, like Quitman and Coahoma, where Cochran increased his margins over McDaniel.
Before the primary, most Mississippi political experts predicted turnout would reach a high of about 250,000. On Tuesday, in a runoff race that usually features a drop in turn out from the primary, more than 360,000 people voted — a remarkably high turnout figure that topped even the number of people who voted in the 2012 GOP presidential primary there.
That strategy, however, is likely to engender discontent from conservatives unhappy that a Republican primary was decided, at least in part, by Democratic voters. It's something McDaniel referenced directly in his concession speech, in which he derided his GOP opponents "abandoning" the conservative movement.
"There is something a bit strange, there is something a bit unusual about a Republican primary that is decided by liberal Democrats," McDaniel said, drawing big cheers from his supporters. "So much for bold colors. So much for principle."
The state senator offered nothing in way of support for Cochran during his speech and instead noted what he said were "dozens" of irregularities at the polls today. Citing Mississippi law, conservatives had expressed concern before the runoff that Democrats voting on Tuesday would do so illegally.
"Today, the conservative movement took a back seat to liberal Democrats in the state of Mississippi," McDaniel said.
In the bigger picture, Cochran's victory is also a major coup for Senate Republicans. McDaniel was last of the candidates they feared could win the party's nomination who could emerge as a Todd Akin-like figure — someone who could give Democrats a chance even in Deep South Mississippi. Worse, they feared anything controversial he said would go national in the same way Akin's comment about rape did in 2012, damaging the party's chances of retaking the Senate.