The Republican Party avoided a demoralizing upset Tuesday when it forced Democrat Jon Ossoff into a special election runoff to fill a vacant conservative Georgia House district.

Ossoff finished first in a crowded field dominated by Republicans. But he appears to have fallen short of 50 percent, and must advance to a runoff where his Republican opponent will be favored to win the suburban Atlanta seat formerly held by Health and Human Services Secretary Tom Price.

It's the expected outcome in a district held by the GOP since Newt Gingrich captured the 6th in 1978. Yet, it was hardly certain three weeks ago, when the super PAC aligned with House Speaker Paul Ryan urgently stepped in with millions in money and manpower.

"If we had waited another couple of weeks, it would have been too late," said Corry Bliss, executive director of Congressional Leadership Fund, in an interview in which he shared the super PAC's strategy.

On March 24, strategists with CLF reviewed results from a fresh opinion poll the group conducted in Georgia's 6th district. They were concerned by what they saw.

Reliable Republican voters in this affluent enclave were tuning out, turned off by their party's candidates, who were bickering among themselves as they scrambled for a spot in the presumed runoff.

Ossoff, boosted by a combination of President Trump's middling approval ratings, the collapse of the GOP healthcare bill, and millions of dollars of in unchallenged advertising on local television, was at 37 percent on the ballot, with a 43 percent personal favorable rating, "and gaining" momentum.

Bliss said that CLF would have preferred to husband its resources for what it presumes could be a tough midterm election, as is often the case for the party that holds the White House. Instead, the group budgeted more than $3 million, since spent, on advertising and field operations, for a rescue mission. The National Republican Congressional Committee also joined the fray.

The day after CLF reviewed its alarming poll, Bliss closed the group's Des Moines field office, punishment for Iowa Rep. David Young's opposition to his party's healthcare repeal bill, and shifted deputy field director Evan Albertson to Atlanta to run point in Georgia 6.

Albertson opened a field office there three days later, and, along with CLF data director Ryan Terrill oversaw a full-time paid field team of 100 that has knocked on doors seven days a week since. The super PAC contracted with a firm that provided door-knocking services, but worked a deal in which CLF ran the personnel.

The group's data crunchers paid extra close attention to a universe of 96,000 Republicans that it identified as voting in the 2016 presidential primary and at least one previous GOP primary, and that were most likely to vote with encouragement.

"CLF was the first group involved in Georgia's special election, and it was our mission to define Ossoff as dishonest and inept through a strong ground game and aggressive advertising efforts," Bliss said.

By the time CLF dropped its first ad and put its first field team on the street to knock on doors, Ossoff had outgunned Republicans on television by a whopping 3,829 gross ratings points; the Democrats and affiliated groups had dumped in money and personnel worth nearly $10 million.

From the Democrats' perspective, it makes sense, even though they were pegging their hopes on an untested, 30 year-old former congressional aide who lives just outside the district. Trump defeated Hillary Clinton there in November by just 1.5 percentage points, even as Price was won re-election with 62 percent.

"This is a solid Republican seat in which Democratic performance has lingered in mid-30's over the past three election cycles," said Ed Espinoza, a Democratic strategist.

This enclave, described by Republican insiders as more like the upscale Washington, D.C., suburbs of Northern Virginia than the traditional South, is the kind of seat Democrats must win next year if they are going to challenge the GOP for the House majority.

"It's not a Southern district," a Republican operative said. "It's like living in Fairfax."

From January through late March, as Ossoff campaigned aggressively and virtually unchecked, he raised his personal favorable rating from just under 10 percent to 43 percent (25.6 percent rated him unfavorably) in the CLF poll.

Additional data in the group's surveys suggested that Ryan, the House speaker from Wisconsin, was a greater asset in the campaign to gin up Republican turn out, than was Trump. Tying Ossoff to House Minority Leader Nancy Pelosi, D-Calif., proved especially effective.

In an April poll the group conducted, respondents by a 62 percent to 26 percent margin said they preferred a candidate who would work with Ryan if elected to Congress, over one who would work with Pelosi.

And so Pelosi's picture was featured prominently in CLF's digital and print advertising. The group, which plans to remain active in the runoff campaign, plans to use similar messaging in round two.

Correction: Basd on information provided in error by CLF, the original version of this story mis-stated Ossof's level of support in a March poll conducted for the super PAC. CLF has since provided the correct information and the story has been adjusted.