By Veronica Stracqualursi, CNN

(CNN) -- Georgia's secretary of state announced Wednesday that the state will conduct an audit of the 2020 presidential race, recounting by hand the millions of ballots cast in the state, where President-elect Joe Biden is leading.

"With the margin being so close, it will require a full by hand recount in each county," Secretary of State Brad Raffensperger, a Republican, said at a news conference in Atlanta. "This will help build confidence."

"It will be an audit, a recount and a recanvas all at once," he added.

Raffensperger's announcement comes as he has faced pressure from President Donald Trump's campaign for a recount, calls from fellow Georgia Republicans to resign and accusations of mismanaging the election process.

Attention has turned to Georgia where both two high-stakes US Senate races appear headed for January runoffs and is causing friction among Republicans in the state. Earlier this week, the two GOP senators, Kelly Loeffler and David Perdue, fighting for reelection, demanded Raffensperger resign from office, accusing him without evidence of failing to "deliver honest and transparent elections."

CNN has not projected a winner in the Georgia presidential race, but Biden currently leads Trump by more than 14,000 votes in the state -- a lead that Raffensperger previously said is "unlikely" to be overtaken in a recount.

CNN has projected that Biden will win the presidential election. Trump has not conceded in the race, and instead has made unfounded claims about widespread voter fraud and mail-in ballots.

The Georgia Republican Party and US Rep. Doug Collins, a Georgia Republican who's leading the Trump campaign's recount efforts in the state, on Tuesday requested a pre-certification "manual hand recount of every ballot cast within the State of Georgia" for president.

Collins and the Trump campaign on Wednesday celebrated the recount decision from the Georgia secretary of state as a victory for "integrity" and "transparency."

"This is an important first step in the process to ensure that the election was fair and that every legal vote was counted," Trump campaign communications director Tim Murtaugh said in a call with reporters.

During Wednesday's press conference, Raffensperger denied that the Trump campaign influenced the state's decision.

"We're doing this because it's really what makes the most sense," he said. "With the national significance of this race, and the closeness of this race, we have to run a statewide audit."

Raffensperger said he expects the recount to be done in time for Georgia's certification of the presidential results, which has a November 20 deadline. The Trump campaign is trying to delay certification in some key states as part of a longshot attempt to overturn the results through the Electoral College.

Raffensperger said he hopes to start the recount before the week ends. So far, 97 of Georgia's 159 counties have already certified their results, but all of the county certifications are still required by Friday, he said.

He said he would officially designate the presidential race as the subject of the risk limiting audit later Wednesday.

Raffensperger said once the results are certified on November 20, a candidate within the 0.5% margin will still be able to request a "recount," but that it would be a "scanned recount" done by machines.

He acknowledged that the audit would be expensive and "a heavy lift" and that election workers will be working overtime.

Typically, risk limiting audits like these only examine a small sample of the votes, but Raffensperger cited the narrow margin as the reason officials will re-check every ballot cast in the presidential race.

This story has been updated with additional details.