But if their challengers, Jon Ossoff and the Rev. Raphael Warnock, win both races, then Democrats will reach a crucial 50-seat threshold in the Senate. Ties are broken in the Senate by the vice president, meaning Kamala Harris will be the deciding factor starting Jan. 20.

Add that to Democrats’ existing majority in the U.S. House and new control of the executive branch, and it would create a unified government for the first two years of the Biden administration. Enormous power comes with control in both chambers plus the executive branch.

The idea of controlling nearly all of Washington was so tantalizing for Senate Democratic Leader Chuck Schumer that he told a crowd of New Yorkers celebrating the general election results: “Now we take Georgia, and then we change the world. Now we take Georgia, and then we change America!”

Former President Barack Obama shared a similar message last week on a Zoom call with Warnock and Ossoff supporters. “This is not just about Georgia,” Obama said. “This is about America, and this is about the world.”

Republicans have used those words against Ossoff and Warnock in ads and during campaign rallies, warning conservative voters that the two Senate seats are practically the only thing standing between America and ruin.

“The Democrats want to fundamentally change America. And the agent of change is my opponent, radical liberal Raphael Warnock,” Loeffler said during a debate last week.

Perdue goes one step further. “This total control, leftist agenda Democrats are trying to perpetrate on America, we’re not going to let that happen,” he told Augusta radio station WGAC this week.

Although Republicans have warned voters that Democratic control of the Senate would allow Biden to implement a socialist agenda, that is an exaggeration of his relatively moderate platform. Neither Biden nor Democratic leaders in the Senate have supported defunding the police or the Green New Deal, initiatives that conservatives say would be on the table if Warnock and Ossoff win in November.

In reality, the difference of a seat or two won’t guarantee either party a lock on every issue. A slim majority for either party means swing votes such as Sen. Joe Manchin, D-West Virginia, and Susan Collins, R-Maine, will remain key components of building a coalition on weighty measures.

Plus, the 50-50 split of members would likely mean that Schumer and Republican Leader Mitch McConnell would broker a power-sharing agreement like the one drafted after the 2000 election produced a similar scenario.

Still, interviews with senators, former congressional staffers and legislative experts revealed a broad consensus that winning the Georgia races and controlling the Senate will be monumentally important to either party in the Biden administration — above and beyond the vote count.

McConnell showed during the Obama years what can happen when the Senate leader throws up a roadblock at virtually every turn. He famously said in 2010 that the “the single most important thing” was making Obama a one-term president.

When Trump moved into the White House, McConnell led the Senate toward a much friendlier posture. The scores of federal judges that have been confirmed, particularly the speedy installation of Supreme Court Justice Amy Coney Barrett, highlighted the shift. The majority-Republicans caucus also voted against having Trump removed from office after his impeachment trial.

The Georgia runoffs will determine which type of Senate leadership will confront Biden, at least for the first two years of his tenure.

‘Night and day’

“It’s as close to a night-and-day contrast as you can get,” Norm Ornstein, a scholar at the American Enterprise Institute, said about the practical differences of a Republican Senate compared with a Democratic Senate that Georgians will get to decide.

“It’s about who is setting the agenda, deciding what comes up, what doesn’t get a vote and what gets buried,” Ornstein said.

Among the big-ticket items Ornstein said could be considered under Democratic control of the Senate — tax increases on the rich and corporations, a major infrastructure package, additional COVID-19 relief and economic stimulus. Other, more comprehensive legislation could include climate change, campaign finance and the John Lewis Voting Rights Act, which would restore voter protections eroded by a 2013 Supreme Court ruling.

Add to that the fate of the Affordable Care Act, marijuana decriminalization, criminal justice legislation and other liberal wish-list items.

“If Democrats are not in the majority, none of those things have to come up,” Ornstein said.

Doug Heye, a former adviser to GOP House Majority Leader Eric Cantor, said: “This is about leverage. If you have a chamber, you have leverage. If you don’t, you do not.”

Heye said unified control of Congress and the White House has been key to previous administration’s biggest victories. Obama needed a Democratic House and Senate to pass the Affordable Care Act in 2010, while Trump could not have passed his massive tax cuts in 2017 without Republicans controlling both chambers.

“It gets to exactly what should be Loeffler and Perdue’s best argument, that they’re not allowed to make right now, which is being the check and balance on the Biden administration,” Heye said.

Because Trump and his supporters are still contesting the outcome of the election in Georgia and other swing states, supporters of Perdue and Loeffler worry that their “firewall” message is being drowned out or at least put on the back burner. Their success on Jan. 5 depends largely on conservative turnout and convincing voters that Perdue and Loeffler are the only way to protect the Trump legacy during a Biden administration.

Republicans use the term “firewall” to describe the incumbents’ power in this scenario. With Loeffler and Perdue remaining in Washington, their supporters say, they can help block liberal initiatives from becoming federal law.

Even Collins, who is considered the Senate’s most bipartisan member, described a doom-and-gloom scenario if Republicans lose their majority.

“There is a far-left agenda that I think would be very harmful to our country,” she told The Atlanta Journal-Constitution. “And I’m afraid that would be pursued if we don’t hold the Georgia Senate seats.”

Another area where Senate control will be crucial is for judicial nominations and Cabinet picks, including Biden’s recent choice of Neera Tanden to head the Office of Management and Budget. Tanden, who leads a liberal think tank, has criticized GOP senators on social media, and now those same members say they are inclined to derail her nomination.

If Democrats win Georgia, Sen. Bernie Sanders would likely chair the Budget Committee that is the gatekeeper for Tanden’s appointment making it to the full Senate. Under a GOP majority, Tanden’s appointment — and others — would be far less certain.

Committee chairmen decide which legislation to bring up for a vote and can slow-walk or shut down the confirmation process for individuals. If Democrats had been in control of the Senate this year, for instance, Barrett would not be a Supreme Court justice.

As Senate majority leader, McConnell decides what the chamber does, when and how. Schumer would become the top dog if Democrats win the two Georgia races. Democrats could also end the 60-vote rule to end debate on legislation, making it easier to move bills and confirmations along over the objection of Republicans.

The filibuster has been a Senate tradition for more than a century but has increasingly become a source of partisan gridlock because the objection of a single member can put it in motion. If Democrats gain control and get rid of the rule, they can approve Biden’s appointments and bring legislation to a vote with a simple majority.

Mike Alexander was the Democratic staff director for the Senate Homeland Security and Governmental Affairs Committee, both when Democrats were in the majority and the minority.

On nominations, Alexander said Democrats would likely work behind the scenes with the Biden team to make sure his nominees move easily.

But if the White House and Senate are run by different parties, Alexander said, the Senate committees can make the process all but impossible. The executive branch makes an appointment and announces it, then senators in the majority “take it to the woodshed.”

A third area where Senate control matters is investigations by committees.

A Republican Senate will likely yield more Hunter Biden and Burisma investigations, not to mention probes into the 2020 elections predicted Ornstein with the American Enterprise Institute. “They’ll attempt to hamstring the administration through the investigative process,” he said.

Georgia power

Because the new Senate will be sworn in Jan. 3, and the runoffs are not until two days later, Ossoff and Warnock would have the least seniority of any members in the chamber.

If they both win, they will be welcomed by Democrats as conquering heroes but still fall to the lowest spot on the totem pole. Since neither has prior elected experience to add to his seniority, the Senate would then rank them by alphabetical order, a matter of no small importance when everything from committee assignments to office space is determined by a senator’s rank in the chamber.

Ossoff would be 99th and Warnock 100th.

Loeffler, who was appointed to her seat a year ago, is currently 99th in terms of seniority.

Now at the end of his first term, Perdue chairs the Banking Committee’s Housing, Transportation, and Community Development Subcommittee and the Seapower Subcommittee of the Senate Armed Services Committee.

Losing a more senior member of the Senate Armed Services Committee could have implications for the state and its 13 military installations, said Ed Lindsey, a former GOP majority whip in the Georgia House who now runs the Atlanta lobbying wing of Dentons, a global law firm.

“Having someone with his level of seniority on Armed Services is extremely important to the state because there are constant attempts within Congress to try to strip away facilities in one state to the benefit of a more senior senator,” Lindsey said. “Seniority matters.”

If Warnock and Ossoff win, they will reap the benefits of being in the controlling party and having amassed political capital that comes with the high-profile nature of their races. Both will have built relationships with Senate colleagues and the Biden administration already — while the president-elect is scheduled to campaign on their behalf this week, senators have hosted virtual events and fundraisers.

They would be in a position to request plum assignments and ensure Georgia gets its fair share of resources and appropriations, especially because holding onto the seats and staying competitive in future statewide races will be a priority for Democrats.

Warnock would also become one of the nation’s most prominent Black politicians, becoming the first African American from the South to serve in the Senate for the Democrats.