Thad Cochran’s political resurrection began with a campaign shakeup and ended with a Hail Mary television ad.

Just three weeks ago, in the dead of night on June 3, the Mississippi senator’s staff sat shaken and dejected, crestfallen at the results of a primary that deprived the six-term incumbent of an electoral majority. With Cochran forced into a runoff fight against an aggressive and energetic challenger, a dark mood shadowed his backers in Washington and Mississippi.

Yet almost immediately, the Cochran coalition began bouncing back. Even on that gloomy night of June 3, Cochran adviser Stuart Stevens was insisting to staffers: “We’re going to win.” One Cochran aide paraphrased Stevens’ primary-night message: “We’re going to figure this out and it’s going to be something you remember for the rest of your life.”

(Full primary election results here)

Back in Washington, Cochran’s most important allies resolved to muffle their anxiety and stick with him for another three weeks. The Chamber of Commerce polled the race, concluded the senator had a difficult but viable path to victory; the group began brainstorming inventive ways to make a splash in the state, culminating with a sensational commercial starring NFL legend Brett Favre. National Republican Senatorial Committee political director Ward Baker, confronted with Beltway pessimism about Cochran’s chances, repeatedly told Republicans in D.C.: “We don’t leave our people on the field.”

Within a week, a powerful operation had swung into motion to save the 76-year-old legislator. Rather than making peace with his firebrand challenger, state and national Republicans redoubled their efforts to tear down Chris McDaniel, whom they considered a political lightweight taking advantage of a virulently anti-Washington mood. In interviews on the day and night of the runoff vote, strategists and party leaders described the campaign as a near-perfect turnaround – considering the slimness of Cochran’s victory, it had to be.

By the time the second round of balloting rolled around on June 24, a collection of groups that might be dubbed the Emergency Committee for Mississippi had spent millions on new television ads, knocked on tens of thousands of doors and reached out to voters – including African-Americans and Democrats – who had likely never voted before in a GOP primary.

The hoped-for payoff came Tuesday night, when Cochran bested McDaniel by some 6,400 votes – a margin of less than 2 percentage points. In a gut punch to conservative activists, Cochran’s survival proved just how much swat national party leaders have when they compete to win by any means necessary.

Joe Sanderson, Cochran’s finance chair, said he always believed that Cochran would win once his legions of admirers realized what was truly at stake. “I think they came out en masse,” Sanderson said. “I’ll be honest with you, I think some African-Americans came out to support him – I don’t know that, I believe that – because they did not want Chris McDaniel and the tea party to win.”

Sanderson, with a confidence matched by few in the Cochran camp, added that he was “not surprised” by the result: “I believed all the time that Sen. McDaniel got all the votes he was going to get in the first primary.”

All in – again

For the pro-Cochran alliance, the race came down to a huge strategic gamble: That the universe of Mississippians who wanted to see Cochran back in the Senate was substantially larger than the group that voted in the primary – and that rather than serving as a death knell for Cochran, the June 3 ballot would serve instead as a wake-up call for apathetic Mississippians.

Dogged ahead of the primary by complaints about a lackluster field program and an unfocused campaign message (and candidate), Cochran’s campaign moved swiftly to reorient its operations for a second election on June 24. Austin Barbour, a top Cochran adviser and former campaign manager for Sen. Roger Wicker, took over the leadership of the organization. Former state GOP Chairman Brad White joined the team to help drive the get-out-the-vote effort. Kirk Sims, up to that point the top staffer on the race, stepped back for personal reasons.

The NRSC gave its field staff a weekend off – and then redeployed them back to the state. Before the primary, the committee had several dozen campaign workers on the ground knocking on doors for Cochran. For the runoff, 45 staff members and volunteers returned. Targeting high-propensity Republican voters, they knocked on 50,000 doors between the two votes. From the basement of the NRSC, campaign workers placed 18,000 calls into Mississippi.

In Washington, a gang of senators dived back into the race. Just a week after the primary, Senate Minority Leader Mitch McConnell headlined a fundraiser that raised more than $800,000 for Cochran. He told assembled supporters in no uncertain terms: “We are going to win it.”

Senators fired off big PAC checks to Cochran. Some worked the phones for him themselves, Wicker chief among them. NRSC senior staff, including executive director Rob Collins and finance director Heather Larison, squeezed every penny they could out of Washington for their embattled colleague. Haley Barbour, the former Mississippi governor, was dialing for runoff dollars as soon as the June 3 vote ended in a deadlock.

Most controversially – and perhaps most importantly – the Mississippi super PAC formed to support Cochran’s reelection shifted its resources dramatically from television advertising to get-out-the-vote operations. Depleted after an all-out effort ahead of June 3, the group went back to its biggest donors for more help. In one case, it secured a $100,000 check from Silicon Valley billionaire Sean Parker, on top of the quarter-million dollars the Napster co-founder had already given to the cause.

But this time, the Mississippi Conservative PAC didn’t spend a dime on television or radio. Instead, the group – headed by Republican National Committeeman Henry Barbour –spent untold sums identifying and turning out longer-shot voters, including non-Republicans and African-Americans who were unlikely to have participated in the first vote.

Cochran spokesman Jordan Russell said the senator’s operation quickly pivoted toward running a kind of race that’s rare in Mississippi and unheard of in most other states. “The campaign’s focus, from the second we woke up on June 4, was to win the blocking and tackling of a runoff in Mississippi,” Russell said. “And we knew how to do it. We knew what to do.”

By ALEXANDER BURNS | 6/25/14 5:02 AM EDT Updated: 6/26/14 11:51 AM EDT